diff --git a/workflow/engine/classes/model/Event.php b/workflow/engine/classes/model/Event.php
index de817500a..0ee3935b9 100644
--- a/workflow/engine/classes/model/Event.php
+++ b/workflow/engine/classes/model/Event.php
@@ -771,11 +771,11 @@ class Event extends BaseEvent {
   function Exists ( $sUid ) {
     try {
       $oObj = EventPeer::retrieveByPk($sUid);
-      return (get_class($oObj) == 'Event');
+      return (is_object($oObj) && get_class($oObj) == 'Event');
     }
     catch (Exception $oError) {
       throw($oError);
     }
   }
 } // Event
-?>
\ No newline at end of file
+?>