Fix bug where we used UserID objects instead of strigns

1 files changed, 2 insertions, 1 deletions

diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py

index eb638fe50a..3e41d7a46b 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -325,7 +325,8 @@ 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)