diff --git a/src/c3nav/editor/changes.py b/src/c3nav/editor/changes.py
index 9baf2eef..0caf1971 100644
--- a/src/c3nav/editor/changes.py
+++ b/src/c3nav/editor/changes.py
@@ -474,7 +474,7 @@ class ChangedObjectCollection(BaseSchema):
                     except FieldDoesNotExist:
                         problems.get_object(changed_obj.obj).field_does_not_exist.add(field_name)
                         continue
-                    if field.related_model.app_name != "mapdata":
+                    if field.related_model._meta.app_name != "mapdata":
                         continue
                     referenced_objects.setdefault(
                         field.related_model._meta.model_name, set()