diff --git a/application/controllers/admin/NotificationController.php b/application/controllers/admin/NotificationController.php
index 071fe024227..2a75d7835a4 100644
--- a/application/controllers/admin/NotificationController.php
+++ b/application/controllers/admin/NotificationController.php
@@ -88,7 +88,7 @@ public function clearAllNotifications($surveyId = null)
             'entity = \'user\' AND entity_id = ' . Yii::app()->user->id
         );
 
-        if ($surveyId)
+        if (is_int($surveyId))
         {
             Notification::model()->deleteAll(
                 'entity = \'survey\' AND entity_id = ' . $surveyId