diff --git a/lib/models/room-state.js b/lib/models/room-state.js
index d5cf12bf8..b4064dac5 100644
--- a/lib/models/room-state.js
+++ b/lib/models/room-state.js
@@ -224,6 +224,20 @@ RoomState.prototype.getUserIdsWithDisplayName = function(displayName) {
     return this._displayNameToUserIds[displayName] || [];
 };
 
+/**
+ * Returns true if the given MatrixClient has permission to send a state
+ * event of type `stateEventType` into this room.
+ * @param {string} type The type of state events to test
+ * @param {MatrixClient}  The client to test permission for
+ * @return {boolean} true if the given client should be permitted to send
+ *                        the given type of state event into this room,
+ *                        according to the room's state.
+ */
+RoomState.prototype.mayClientSendStateEvent = function(stateEventType, cli) {
+    if (cli.isGuest()) return false;
+    return this.maySendStateEvent(stateEventType, cli.credentials.userId);
+}; 
+
 /**
  * Returns true if the given user ID has permission to send a state
  * event of type `stateEventType` into this room.