--- a/plugins/muc/muc.lib.lua	Tue Apr 01 15:26:40 2014 +0200
+++ b/plugins/muc/muc.lib.lua	Tue Apr 01 10:02:58 2014 -0400
@@ -1060,7 +1060,7 @@
 	if actor_jid == true then return true; end
 
 	local actor = self._occupants[self._jid_nick[actor_jid]];
-	if actor.role == "moderator" then
+	if actor and actor.role == "moderator" then
 		if occupant.affiliation ~= "owner" and occupant.affiliation ~= "admin" then
 			if actor.affiliation == "owner" or actor.affiliation == "admin" then
 				return true;