diff --git a/lib/client.js b/lib/client.js
index 4892eb239..b7a4d7f09 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -592,6 +592,9 @@ MatrixClient.prototype.isRoomEncrypted = function(roomId) {
 
 /**
  * Get the room for the given room ID.
+ * This function will return a valid room for any room for which a Room event
+ * has been emitted. Note in particular that other events, eg. RoomState.members
+ * will be emitted for a room before this function will return the given room.
  * @param {string} roomId The room ID
  * @return {Room} The Room or null if it doesn't exist or there is no data store.
  */