diff --git a/engine.py b/engine.py
index 87aeaad..99d649b 100644
--- a/engine.py
+++ b/engine.py
@@ -65,7 +65,7 @@ def has_ui(self):
         # a QApplication has been created.
         if self._has_qt:
             from tank.platform.qt import QtGui
-            return QtGui.qApp is not None
+            return QtGui.QApplication.instance() is not None
         else:
             return False
 
@@ -129,7 +129,7 @@ def execute_command(self, cmd_key, args):
             
             # start up our QApp now, if none is already running
             qt_application = None
-            if not QtGui.qApp:
+            if not QtGui.QApplication.instance():
                 QtGui.QApplication.setLibraryPaths([])
                 qt_application = QtGui.QApplication([])
                 qt_application.setWindowIcon(QtGui.QIcon(self.icon_256))