1 files changed, 2 insertions, 1 deletions
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 1ced7d0613..d46bc308b4 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -360,7 +360,8 @@ class RoomMemberHandler(BaseRoomHandler):
         )
 
         snapshot = yield self.store.snapshot_room(
-            room_id, joinee, RoomMemberEvent.TYPE, joinee
+            room_id, joinee.to_string(), RoomMemberEvent.TYPE,
+            joinee.to_string()
         )
 
         yield self._do_join(new_event, snapshot, room_host=host, do_auth=True)