diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 9d745174c..f8999d64d 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -599,7 +599,7 @@ class RoomMembershipRestServlet(ClientV1RestServlet):
     def register(self, http_server):
         # /rooms/$roomid/[invite|join|leave]
         PATTERNS = ("/rooms/(?P<room_id>[^/]*)/"
-                    "(?P<membership_action>join|invite|leave|ban|unban|kick|forget)")
+                    "(?P<membership_action>join|invite|leave|ban|unban|kick)")
         register_txn_path(self, PATTERNS, http_server)
 
     @defer.inlineCallbacks