diff --git a/ndb_orm/model.py b/ndb_orm/model.py
index 6f6cba0..e54f79c 100644
--- a/ndb_orm/model.py
+++ b/ndb_orm/model.py
@@ -1312,7 +1312,7 @@ def _apply_to_values(self, entity, function):
     else:
       if value is not None:
         newvalue = function(value)
-        if newvalue is not None and newvalue is not value:
+        if newvalue is not None:
           self._store_value(entity, newvalue)
           value = newvalue
     return value