diff --git a/clientapi/routing/sendevent.go b/clientapi/routing/sendevent.go
index b8a7fe98f..70bf72f88 100644
--- a/clientapi/routing/sendevent.go
+++ b/clientapi/routing/sendevent.go
@@ -108,7 +108,7 @@ func SendEvent(
 	// via key if it is present, otherwise other servers won't be able to auth
 	// the event if the room is set to the "restricted" join rule.
 	if eventType == gomatrixserverlib.MRoomMember {
-		delete(r, "join_authorised_by_users_server")
+		delete(r, "join_authorised_via_users_server")
 	}
 
 	evTime, err := httputil.ParseTSParam(req)