diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000000..dfdb8b771c
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+*.sh text eol=lf
diff --git a/detectron2/modeling/meta_arch/panoptic_fpn.py b/detectron2/modeling/meta_arch/panoptic_fpn.py
index b31e1c8dc0..772286a1bb 100644
--- a/detectron2/modeling/meta_arch/panoptic_fpn.py
+++ b/detectron2/modeling/meta_arch/panoptic_fpn.py
@@ -123,7 +123,7 @@ def forward(self, batched_inputs):
             self.backbone.size_divisibility,
             self.sem_seg_head.ignore_value,
             self.backbone.padding_constraints,
-        ).tensor
+        ).tensor.long()
         sem_seg_results, sem_seg_losses = self.sem_seg_head(features, gt_sem_seg)
 
         gt_instances = [x["instances"].to(self.device) for x in batched_inputs]