diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index b7b9651fd4..fd258dc58b 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -281,7 +281,7 @@ class RoomCreationHandler(BaseHandler):
             (EventTypes.Encryption, ""),
             (EventTypes.ServerACL, ""),
             (EventTypes.RelatedGroups, ""),
-            (EventTypes.Widgets, ""),
+            (EventTypes.Widgets, None),
         )
 
         old_room_state_ids = yield self.store.get_filtered_current_state_ids(