--- a/util/pubsub.lua	Fri Dec 03 16:36:13 2010 +0100
+++ b/util/pubsub.lua	Sun Dec 05 02:46:08 2010 +0100
@@ -17,7 +17,14 @@
 end
 
 function service:remove_subscription(node, actor, jid)
-	self.nodes[node].subscribers[jid] = nil;
+	local node_obj = self.nodes[node];
+	if not node_obj then
+		return false, "item-not-found";
+	end
+	if not node_obj.subscribers[jid] then
+		return false, "not-subscribed";
+	end
+	node_obj.subscribers[jid] = nil;
 	return true;
 end