diff --git a/LICENSE b/LICENSE
index 08ddefd04..9efa6fbc9 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,12 +1,12 @@
-		    GNU GENERAL PUBLIC LICENSE
-		       Version 2, June 1991
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
 
  Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 
-			    Preamble
+                            Preamble
 
   The licenses for most software are designed to take away your
 freedom to share and change it.  By contrast, the GNU General Public
@@ -56,7 +56,7 @@ patent must be licensed for everyone's free use or not licensed at all.
   The precise terms and conditions for copying, distribution and
 modification follow.
 
-		    GNU GENERAL PUBLIC LICENSE
+                    GNU GENERAL PUBLIC LICENSE
    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
 
   0. This License applies to any program or other work which contains
@@ -255,7 +255,7 @@ make exceptions for this.  Our decision will be guided by the two goals
 of preserving the free status of all derivatives of our free software and
 of promoting the sharing and reuse of software generally.
 
-			    NO WARRANTY
+                            NO WARRANTY
 
   11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
 FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
@@ -277,9 +277,9 @@ YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
 PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGES.
 
-		     END OF TERMS AND CONDITIONS
+                     END OF TERMS AND CONDITIONS
 
-	    How to Apply These Terms to Your New Programs
+            How to Apply These Terms to Your New Programs
 
   If you develop a new program, and you want it to be of the greatest
 possible use to the public, the best way to achieve this is to make it
@@ -304,8 +304,7 @@ the "copyright" line and a pointer to where the full notice is found.
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License along
-    with this program; if not, write to the Free Software Foundation, Inc.,
-    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+    with this program; if not, see <https://www.gnu.org/licenses/>.
 
 Also add information on how to contact you by electronic and paper mail.
 
@@ -329,12 +328,11 @@ necessary.  Here is a sample; alter the names:
   Yoyodyne, Inc., hereby disclaims all copyright interest in the program
   `Gnomovision' (which makes passes at compilers) written by James Hacker.
 
-  <signature of Ty Coon>, 1 April 1989
-  Ty Coon, President of Vice
+  <signature of Moe Ghoul>, 1 April 1989
+  Moe Ghoul, President of Vice
 
 This General Public License does not permit incorporating your program into
 proprietary programs.  If your program is a subroutine library, you may
 consider it more useful to permit linking proprietary applications with the
 library.  If this is what you want to do, use the GNU Lesser General
 Public License instead of this License.
-
diff --git a/nml/__init__.py b/nml/__init__.py
index 5c0e87ff2..315c06b68 100644
--- a/nml/__init__.py
+++ b/nml/__init__.py
@@ -1,14 +1 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
diff --git a/nml/_lz77.c b/nml/_lz77.c
index 95a3f9309..ab0913148 100644
--- a/nml/_lz77.c
+++ b/nml/_lz77.c
@@ -1,17 +1,4 @@
-/* NML is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * NML is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with NML; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 
 /**
  * @file
diff --git a/nml/actions/__init__.py b/nml/actions/__init__.py
index 5c0e87ff2..315c06b68 100644
--- a/nml/actions/__init__.py
+++ b/nml/actions/__init__.py
@@ -1,14 +1 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
diff --git a/nml/actions/action0.py b/nml/actions/action0.py
index be0249100..6920cdc7a 100644
--- a/nml/actions/action0.py
+++ b/nml/actions/action0.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, grfstrings, nmlop
 from nml.actions import action4, action6, action7, actionD, base_action
diff --git a/nml/actions/action0properties.py b/nml/actions/action0properties.py
index 8e91963b0..97f85495e 100644
--- a/nml/actions/action0properties.py
+++ b/nml/actions/action0properties.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import itertools
 
diff --git a/nml/actions/action1.py b/nml/actions/action1.py
index fcdf472eb..7fab666d0 100644
--- a/nml/actions/action1.py
+++ b/nml/actions/action1.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml.actions import base_action, real_sprite, action2
 
diff --git a/nml/actions/action10.py b/nml/actions/action10.py
index b2db02e6f..1a5e31460 100644
--- a/nml/actions/action10.py
+++ b/nml/actions/action10.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml.actions import base_action
 
diff --git a/nml/actions/action11.py b/nml/actions/action11.py
index 6cf698d79..a9c7937d7 100644
--- a/nml/actions/action11.py
+++ b/nml/actions/action11.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 """
 Action 11 support classes (sounds).
diff --git a/nml/actions/action12.py b/nml/actions/action12.py
index 65e10ada3..2222f2e62 100644
--- a/nml/actions/action12.py
+++ b/nml/actions/action12.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic
 from nml.actions import base_action, real_sprite
diff --git a/nml/actions/action14.py b/nml/actions/action14.py
index 1d5a45a08..37773dcd2 100644
--- a/nml/actions/action14.py
+++ b/nml/actions/action14.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, grfstrings
 from nml.actions import base_action
diff --git a/nml/actions/action2.py b/nml/actions/action2.py
index 0ccdf2950..b58106193 100644
--- a/nml/actions/action2.py
+++ b/nml/actions/action2.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, global_constants
 from nml.actions import base_action
diff --git a/nml/actions/action2layout.py b/nml/actions/action2layout.py
index 1371e6340..22ea08505 100644
--- a/nml/actions/action2layout.py
+++ b/nml/actions/action2layout.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, nmlop
 from nml.actions import action0, action1, action2, action2real, action2var, action6, actionD, real_sprite
diff --git a/nml/actions/action2production.py b/nml/actions/action2production.py
index 07f7388a7..3852ca3db 100644
--- a/nml/actions/action2production.py
+++ b/nml/actions/action2production.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants, nmlop
 from nml.actions import action2, action2var, action6, actionD
diff --git a/nml/actions/action2random.py b/nml/actions/action2random.py
index 04343778f..ac1ab1a7a 100644
--- a/nml/actions/action2random.py
+++ b/nml/actions/action2random.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, nmlop
 from nml.actions import action2, action2real, action2var, action6
diff --git a/nml/actions/action2real.py b/nml/actions/action2real.py
index 8f73650b1..8244a4639 100644
--- a/nml/actions/action2real.py
+++ b/nml/actions/action2real.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 from nml.actions import action1, action2
diff --git a/nml/actions/action2var.py b/nml/actions/action2var.py
index 128e6237e..469217bf9 100644
--- a/nml/actions/action2var.py
+++ b/nml/actions/action2var.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants, nmlop
 from nml.actions import action2, action2real, action2var_variables, action4, action6, actionD
diff --git a/nml/actions/action2var_variables.py b/nml/actions/action2var_variables.py
index 0a30dc615..923ab42c1 100644
--- a/nml/actions/action2var_variables.py
+++ b/nml/actions/action2var_variables.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, nmlop
 
diff --git a/nml/actions/action3.py b/nml/actions/action3.py
index 8fcb599fe..66d2182ba 100644
--- a/nml/actions/action3.py
+++ b/nml/actions/action3.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants, nmlop
 from nml.actions import (
diff --git a/nml/actions/action3_callbacks.py b/nml/actions/action3_callbacks.py
index e88ec4bf8..9e09181b2 100644
--- a/nml/actions/action3_callbacks.py
+++ b/nml/actions/action3_callbacks.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import nmlop
 
diff --git a/nml/actions/action4.py b/nml/actions/action4.py
index 77c65e067..1074839ae 100644
--- a/nml/actions/action4.py
+++ b/nml/actions/action4.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, grfstrings
 from nml.actions import action6, actionD, base_action
diff --git a/nml/actions/action5.py b/nml/actions/action5.py
index 4c16955d1..8cac4af8f 100644
--- a/nml/actions/action5.py
+++ b/nml/actions/action5.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 from nml.actions import base_action, real_sprite
diff --git a/nml/actions/action6.py b/nml/actions/action6.py
index 0f23a0750..c5cc3e3b5 100644
--- a/nml/actions/action6.py
+++ b/nml/actions/action6.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import free_number_list, generic
 from nml.actions import base_action
diff --git a/nml/actions/action7.py b/nml/actions/action7.py
index 44dbf9a28..a1202b6ec 100644
--- a/nml/actions/action7.py
+++ b/nml/actions/action7.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, free_number_list, generic, nmlop
 from nml.actions import action6, action10, actionD, base_action
diff --git a/nml/actions/action8.py b/nml/actions/action8.py
index 6e039e872..58e875ce0 100644
--- a/nml/actions/action8.py
+++ b/nml/actions/action8.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import grfstrings
 from nml.actions import base_action
diff --git a/nml/actions/actionA.py b/nml/actions/actionA.py
index 6798a27c5..f94c3c81f 100644
--- a/nml/actions/actionA.py
+++ b/nml/actions/actionA.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import nmlop
 from nml.actions import action6, actionD, base_action, real_sprite
diff --git a/nml/actions/actionB.py b/nml/actions/actionB.py
index 3071e6ef4..24294f255 100644
--- a/nml/actions/actionB.py
+++ b/nml/actions/actionB.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, grfstrings
 from nml.actions import action6, actionD, base_action
diff --git a/nml/actions/actionD.py b/nml/actions/actionD.py
index 8a8a889f4..e9dfcfde9 100644
--- a/nml/actions/actionD.py
+++ b/nml/actions/actionD.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants, nmlop
 from nml.actions import action6, action7, base_action
diff --git a/nml/actions/actionE.py b/nml/actions/actionE.py
index 1c28956d8..e1b1500eb 100644
--- a/nml/actions/actionE.py
+++ b/nml/actions/actionE.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml.actions import base_action
 
diff --git a/nml/actions/actionF.py b/nml/actions/actionF.py
index 790a92b4c..66a273f97 100644
--- a/nml/actions/actionF.py
+++ b/nml/actions/actionF.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 """
 Code for storing and generating action F
diff --git a/nml/actions/base_action.py b/nml/actions/base_action.py
index 774e75548..928e7f006 100644
--- a/nml/actions/base_action.py
+++ b/nml/actions/base_action.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 
 class BaseAction:
diff --git a/nml/actions/real_sprite.py b/nml/actions/real_sprite.py
index 5cb016965..102f3e53c 100644
--- a/nml/actions/real_sprite.py
+++ b/nml/actions/real_sprite.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 try:
     from PIL import Image
diff --git a/nml/actions/sprite_count.py b/nml/actions/sprite_count.py
index db46c4705..fca619ed7 100644
--- a/nml/actions/sprite_count.py
+++ b/nml/actions/sprite_count.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 
 class SpriteCountAction:
diff --git a/nml/ast/__init__.py b/nml/ast/__init__.py
index 5c0e87ff2..315c06b68 100644
--- a/nml/ast/__init__.py
+++ b/nml/ast/__init__.py
@@ -1,14 +1 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
diff --git a/nml/ast/alt_sprites.py b/nml/ast/alt_sprites.py
index a07d17c17..e1e1dedd9 100644
--- a/nml/ast/alt_sprites.py
+++ b/nml/ast/alt_sprites.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.ast import base_statement, sprite_container
diff --git a/nml/ast/assignment.py b/nml/ast/assignment.py
index 99e631099..14b3ebd9d 100644
--- a/nml/ast/assignment.py
+++ b/nml/ast/assignment.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/ast/base_graphics.py b/nml/ast/base_graphics.py
index bb8f5771c..30a4f7b43 100644
--- a/nml/ast/base_graphics.py
+++ b/nml/ast/base_graphics.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic
 from nml.actions import real_sprite
diff --git a/nml/ast/base_statement.py b/nml/ast/base_statement.py
index 01a9f5c4c..c8c0cbc6f 100644
--- a/nml/ast/base_statement.py
+++ b/nml/ast/base_statement.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/ast/basecost.py b/nml/ast/basecost.py
index 286938af6..573da734a 100644
--- a/nml/ast/basecost.py
+++ b/nml/ast/basecost.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants, nmlop
 from nml.actions import action0
diff --git a/nml/ast/cargotable.py b/nml/ast/cargotable.py
index c18dd43bf..73d41a65f 100644
--- a/nml/ast/cargotable.py
+++ b/nml/ast/cargotable.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action0
diff --git a/nml/ast/conditional.py b/nml/ast/conditional.py
index c4465bd60..1acf1ea85 100644
--- a/nml/ast/conditional.py
+++ b/nml/ast/conditional.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, global_constants
 from nml.actions import action7
diff --git a/nml/ast/constant.py b/nml/ast/constant.py
index d7e15dbf1..1277104b8 100644
--- a/nml/ast/constant.py
+++ b/nml/ast/constant.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.ast import base_statement
diff --git a/nml/ast/deactivate.py b/nml/ast/deactivate.py
index 7d254a1f5..491bda068 100644
--- a/nml/ast/deactivate.py
+++ b/nml/ast/deactivate.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic
 from nml.actions import actionE
diff --git a/nml/ast/disable_item.py b/nml/ast/disable_item.py
index f2edf10c5..94570bb6d 100644
--- a/nml/ast/disable_item.py
+++ b/nml/ast/disable_item.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, global_constants
 from nml.actions import action0
diff --git a/nml/ast/error.py b/nml/ast/error.py
index 42cb86880..2fe0dc948 100644
--- a/nml/ast/error.py
+++ b/nml/ast/error.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic
 from nml.actions import actionB
diff --git a/nml/ast/font.py b/nml/ast/font.py
index 12a3b642c..ff7df1281 100644
--- a/nml/ast/font.py
+++ b/nml/ast/font.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic
 from nml.actions import action12
diff --git a/nml/ast/general.py b/nml/ast/general.py
index 93656c637..7e4f8594f 100644
--- a/nml/ast/general.py
+++ b/nml/ast/general.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 from nml.ast import base_statement
diff --git a/nml/ast/grf.py b/nml/ast/grf.py
index 3440b1fd4..28fd5d8c8 100644
--- a/nml/ast/grf.py
+++ b/nml/ast/grf.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants, grfstrings
 from nml.actions import action8, action14
diff --git a/nml/ast/item.py b/nml/ast/item.py
index 87cc32901..99974c24e 100644
--- a/nml/ast/item.py
+++ b/nml/ast/item.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action0, action2, action2var, action3
diff --git a/nml/ast/loop.py b/nml/ast/loop.py
index cf2e861db..cb0331534 100644
--- a/nml/ast/loop.py
+++ b/nml/ast/loop.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, global_constants
 from nml.actions import action7
diff --git a/nml/ast/override.py b/nml/ast/override.py
index 25207dc0a..ab87f6e3b 100644
--- a/nml/ast/override.py
+++ b/nml/ast/override.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action0
diff --git a/nml/ast/produce.py b/nml/ast/produce.py
index 880927fa6..6fa543069 100644
--- a/nml/ast/produce.py
+++ b/nml/ast/produce.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic
 from nml.actions import action2, action2production, action2var
diff --git a/nml/ast/replace.py b/nml/ast/replace.py
index 71c723f4b..a7f5de4c5 100644
--- a/nml/ast/replace.py
+++ b/nml/ast/replace.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action5, actionA
diff --git a/nml/ast/skipall.py b/nml/ast/skipall.py
index 74ca91082..34d084cbc 100644
--- a/nml/ast/skipall.py
+++ b/nml/ast/skipall.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 from nml.actions import action7
diff --git a/nml/ast/snowline.py b/nml/ast/snowline.py
index 95e771fee..e1a332832 100644
--- a/nml/ast/snowline.py
+++ b/nml/ast/snowline.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import datetime
 
diff --git a/nml/ast/sort_vehicles.py b/nml/ast/sort_vehicles.py
index 35d6c744b..2a324c4f4 100644
--- a/nml/ast/sort_vehicles.py
+++ b/nml/ast/sort_vehicles.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action0
diff --git a/nml/ast/sprite_container.py b/nml/ast/sprite_container.py
index 0f91dc1a1..df8de1506 100644
--- a/nml/ast/sprite_container.py
+++ b/nml/ast/sprite_container.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/ast/spriteblock.py b/nml/ast/spriteblock.py
index ad106c402..6497139d4 100644
--- a/nml/ast/spriteblock.py
+++ b/nml/ast/spriteblock.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action2, action2layout, action2real, real_sprite
diff --git a/nml/ast/switch.py b/nml/ast/switch.py
index 0bacd0b5c..21d80d7e7 100644
--- a/nml/ast/switch.py
+++ b/nml/ast/switch.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action2, action2random, action2var
diff --git a/nml/ast/tilelayout.py b/nml/ast/tilelayout.py
index 0b59c3405..e0b9aa02a 100644
--- a/nml/ast/tilelayout.py
+++ b/nml/ast/tilelayout.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action0properties
diff --git a/nml/ast/townnames.py b/nml/ast/townnames.py
index 3370fd713..2d8d50bba 100644
--- a/nml/ast/townnames.py
+++ b/nml/ast/townnames.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import heapq
 
diff --git a/nml/ast/tracktypetable.py b/nml/ast/tracktypetable.py
index d48319eba..f1ca96830 100644
--- a/nml/ast/tracktypetable.py
+++ b/nml/ast/tracktypetable.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, global_constants
 from nml.actions import action0
diff --git a/nml/editors/__init__.py b/nml/editors/__init__.py
index 5c0e87ff2..315c06b68 100644
--- a/nml/editors/__init__.py
+++ b/nml/editors/__init__.py
@@ -1,14 +1 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
diff --git a/nml/editors/extract_tables.py b/nml/editors/extract_tables.py
index 528b7429c..9852e25df 100644
--- a/nml/editors/extract_tables.py
+++ b/nml/editors/extract_tables.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import global_constants, tokens, unit
 from nml.actions import (
diff --git a/nml/editors/kate.py b/nml/editors/kate.py
index 454720062..414e88e6f 100644
--- a/nml/editors/kate.py
+++ b/nml/editors/kate.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml.editors import extract_tables
 
diff --git a/nml/editors/notepadpp.py b/nml/editors/notepadpp.py
index 40703336f..553acd197 100644
--- a/nml/editors/notepadpp.py
+++ b/nml/editors/notepadpp.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml.editors import extract_tables
 
diff --git a/nml/editors/visualstudiocode.py b/nml/editors/visualstudiocode.py
index 3c9ad2191..d4a3c5556 100644
--- a/nml/editors/visualstudiocode.py
+++ b/nml/editors/visualstudiocode.py
@@ -1,15 +1,4 @@
-__license__ = """
-nmlL is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
- nmlL is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
- You should have received a copy of the GNU General Public License along
-with nmlL; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import json
 from nml.editors import extract_tables
diff --git a/nml/expression/__init__.py b/nml/expression/__init__.py
index 4cef1ef81..8f3175ee3 100644
--- a/nml/expression/__init__.py
+++ b/nml/expression/__init__.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import re
 
diff --git a/nml/expression/abs_op.py b/nml/expression/abs_op.py
index 397818a95..7d45e0bd7 100644
--- a/nml/expression/abs_op.py
+++ b/nml/expression/abs_op.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/array.py b/nml/expression/array.py
index e58e4d85c..f6a54415c 100644
--- a/nml/expression/array.py
+++ b/nml/expression/array.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/base_expression.py b/nml/expression/base_expression.py
index b6580ad28..005ab4a9a 100644
--- a/nml/expression/base_expression.py
+++ b/nml/expression/base_expression.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/bin_not.py b/nml/expression/bin_not.py
index b2d11a107..dd1e5bfaf 100644
--- a/nml/expression/bin_not.py
+++ b/nml/expression/bin_not.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, nmlop
 
diff --git a/nml/expression/binop.py b/nml/expression/binop.py
index fe83c0a45..d6047dda5 100644
--- a/nml/expression/binop.py
+++ b/nml/expression/binop.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, nmlop
 
diff --git a/nml/expression/bitmask.py b/nml/expression/bitmask.py
index a2d3d5d4e..34fec0e9c 100644
--- a/nml/expression/bitmask.py
+++ b/nml/expression/bitmask.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, nmlop
 
diff --git a/nml/expression/boolean.py b/nml/expression/boolean.py
index e80f3712a..27778f170 100644
--- a/nml/expression/boolean.py
+++ b/nml/expression/boolean.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/cargo.py b/nml/expression/cargo.py
index 4530609b7..d1deeca36 100644
--- a/nml/expression/cargo.py
+++ b/nml/expression/cargo.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, global_constants
 
diff --git a/nml/expression/functioncall.py b/nml/expression/functioncall.py
index c8a4ec4af..ec1b9f97d 100644
--- a/nml/expression/functioncall.py
+++ b/nml/expression/functioncall.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import calendar
 import datetime
diff --git a/nml/expression/functionptr.py b/nml/expression/functionptr.py
index 71596d1c4..8c5bc64f8 100644
--- a/nml/expression/functionptr.py
+++ b/nml/expression/functionptr.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/identifier.py b/nml/expression/identifier.py
index 426bdb4b9..7090ad19c 100644
--- a/nml/expression/identifier.py
+++ b/nml/expression/identifier.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, global_constants
 
diff --git a/nml/expression/parameter.py b/nml/expression/parameter.py
index 265b46849..575bd34bf 100644
--- a/nml/expression/parameter.py
+++ b/nml/expression/parameter.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, grfstrings
 
diff --git a/nml/expression/patch_variable.py b/nml/expression/patch_variable.py
index 33f9d50b2..44f77c2d1 100644
--- a/nml/expression/patch_variable.py
+++ b/nml/expression/patch_variable.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/special_parameter.py b/nml/expression/special_parameter.py
index 038edb9f4..34da0b39d 100644
--- a/nml/expression/special_parameter.py
+++ b/nml/expression/special_parameter.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/spritegroup_ref.py b/nml/expression/spritegroup_ref.py
index 834726f92..7b315121b 100644
--- a/nml/expression/spritegroup_ref.py
+++ b/nml/expression/spritegroup_ref.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from itertools import chain
 
diff --git a/nml/expression/storage_op.py b/nml/expression/storage_op.py
index 00f957ced..8d611d55f 100644
--- a/nml/expression/storage_op.py
+++ b/nml/expression/storage_op.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/string.py b/nml/expression/string.py
index d065b64a6..5c3787fab 100644
--- a/nml/expression/string.py
+++ b/nml/expression/string.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from functools import reduce
 
diff --git a/nml/expression/string_literal.py b/nml/expression/string_literal.py
index 8d3dbeb62..6542442cc 100644
--- a/nml/expression/string_literal.py
+++ b/nml/expression/string_literal.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic, grfstrings
 
diff --git a/nml/expression/ternaryop.py b/nml/expression/ternaryop.py
index 2c704fa54..fda8b5202 100644
--- a/nml/expression/ternaryop.py
+++ b/nml/expression/ternaryop.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/expression/variable.py b/nml/expression/variable.py
index fb8c871d8..51755b796 100644
--- a/nml/expression/variable.py
+++ b/nml/expression/variable.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/free_number_list.py b/nml/free_number_list.py
index 252219a80..ba855c5b2 100644
--- a/nml/free_number_list.py
+++ b/nml/free_number_list.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/generic.py b/nml/generic.py
index a39180bce..02cb9b3d7 100644
--- a/nml/generic.py
+++ b/nml/generic.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import os
 import sys
diff --git a/nml/global_constants.py b/nml/global_constants.py
index 7bf9f38c4..e637855e7 100644
--- a/nml/global_constants.py
+++ b/nml/global_constants.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import expression, generic, nmlop
 
diff --git a/nml/grfstrings.py b/nml/grfstrings.py
index 3a67a013a..51b8acbca 100644
--- a/nml/grfstrings.py
+++ b/nml/grfstrings.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import glob
 import os
diff --git a/nml/lz77.py b/nml/lz77.py
index 5733e1b77..7ceedcd15 100644
--- a/nml/lz77.py
+++ b/nml/lz77.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import array
 
diff --git a/nml/main.py b/nml/main.py
index afd2435b2..8ba962c75 100644
--- a/nml/main.py
+++ b/nml/main.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import codecs
 import optparse
diff --git a/nml/nmlop.py b/nml/nmlop.py
index 7d9a9f4f6..c241dbd64 100644
--- a/nml/nmlop.py
+++ b/nml/nmlop.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import operator
 
diff --git a/nml/output_base.py b/nml/output_base.py
index 8f1cf2b63..5e83de072 100644
--- a/nml/output_base.py
+++ b/nml/output_base.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 """
 Abstract base classes that implements common functionality for output classes
diff --git a/nml/output_dep.py b/nml/output_dep.py
index c87bc5201..fac865f65 100644
--- a/nml/output_dep.py
+++ b/nml/output_dep.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # -*- coding: utf-8 -*-
 from nml import output_base
diff --git a/nml/output_grf.py b/nml/output_grf.py
index 2312f3255..41f267b50 100644
--- a/nml/output_grf.py
+++ b/nml/output_grf.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import hashlib
 import os
diff --git a/nml/output_nfo.py b/nml/output_nfo.py
index bcb8ba786..f8c19025d 100644
--- a/nml/output_nfo.py
+++ b/nml/output_nfo.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # -*- coding: utf-8 -*-
 import io
diff --git a/nml/output_nml.py b/nml/output_nml.py
index 9afe84701..48a44700b 100644
--- a/nml/output_nml.py
+++ b/nml/output_nml.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import output_base
 
diff --git a/nml/palette.py b/nml/palette.py
index ad41917b9..568f23aa2 100644
--- a/nml/palette.py
+++ b/nml/palette.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from nml import generic
 
diff --git a/nml/parser.py b/nml/parser.py
index 9df8670d7..675a6d981 100644
--- a/nml/parser.py
+++ b/nml/parser.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 from .ply import yacc
 
diff --git a/nml/spritecache.py b/nml/spritecache.py
index b65d3ba87..f0763ec49 100644
--- a/nml/spritecache.py
+++ b/nml/spritecache.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import array
 import json
diff --git a/nml/spriteencoder.py b/nml/spriteencoder.py
index 71a488141..fea42ddd4 100644
--- a/nml/spriteencoder.py
+++ b/nml/spriteencoder.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import array
 
diff --git a/nml/tokens.py b/nml/tokens.py
index 56e10f6a9..9e1164a12 100644
--- a/nml/tokens.py
+++ b/nml/tokens.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import re
 import sys
diff --git a/nml/unit.py b/nml/unit.py
index afb61901f..287ae7dd0 100644
--- a/nml/unit.py
+++ b/nml/unit.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # Available units, mapping of unit name to L{Unit} objects.
 units = {}
diff --git a/nml/version_info.py b/nml/version_info.py
index 2cc4a4082..1a03a3b70 100644
--- a/nml/version_info.py
+++ b/nml/version_info.py
@@ -1,17 +1,4 @@
-__license__ = """
-NML is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-NML is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License along
-with NML; if not, write to the Free Software Foundation, Inc.,
-51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA."""
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 import os
 import sys