diff --git a/include/class.queue.php b/include/class.queue.php
index 790cedf0fe34f9728ee104ce15614782dc99f4d4..8a39e0f55b9148adf9b1262973c6f79b6744332b 100644
--- a/include/class.queue.php
+++ b/include/class.queue.php
@@ -2145,7 +2145,7 @@ extends VerySimpleModel {
         if (!isset($this->_queue)) {
             $queue = $this->queue;
 
-            if (!$queue && ($queue_id = $this->queue_id))
+            if (!$queue && ($queue_id = $this->queue_id) && is_numeric($queue_id))
                 $queue = CustomQueue::lookup($queue_id);
 
             $this->_queue = $queue;