diff --git a/src/c3nav/editor/models/changeset.py b/src/c3nav/editor/models/changeset.py
index 598ba72b..889bcbd3 100644
--- a/src/c3nav/editor/models/changeset.py
+++ b/src/c3nav/editor/models/changeset.py
@@ -188,7 +188,9 @@ class ChangeSet(models.Model):
         r = tuple((pk, values[name]) for pk, values in self.updated_existing.get(model, {}).items() if name in values)
         return r
 
-    def get_changed_object(self, model, pk=None) -> ChangedObject:
+    def get_changed_object(self, obj) -> ChangedObject:
+        model = obj.__class__
+        pk = obj.pk
         if pk is None:
             return ChangedObject(changeset=self, model_class=model)
 
diff --git a/src/c3nav/editor/wrappers.py b/src/c3nav/editor/wrappers.py
index 9d864948..c701fc3e 100644
--- a/src/c3nav/editor/wrappers.py
+++ b/src/c3nav/editor/wrappers.py
@@ -186,7 +186,7 @@ class ModelInstanceWrapper(BaseWrapper):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         if self._obj.pk is not None:
-            self._changeset.get_changed_object(self._obj.__class__, self._obj.pk).apply_to_instance(self)
+            self._changeset.get_changed_object(self._obj).apply_to_instance(self)
 
     def __eq__(self, other):
         if isinstance(other, BaseWrapper):
@@ -234,10 +234,10 @@ class ModelInstanceWrapper(BaseWrapper):
         """
         Create changes in changeset instead of saving.
         """
-        self._changeset.get_changed_object(self._obj.__class__, self.pk).save_instance(self)
+        self._changeset.get_changed_object(self._obj).save_instance(self)
 
     def delete(self):
-        self._changeset.get_changed_object(self._obj.__class__, self.pk).mark_deleted()
+        self._changeset.get_changed_object(self._obj).mark_deleted()
 
 
 def get_queryset(func):