diff --git a/lib/Cron/Workers/Scheduler.php b/lib/Cron/Workers/Scheduler.php
index f6d83c7602..d10de85f96 100644
--- a/lib/Cron/Workers/Scheduler.php
+++ b/lib/Cron/Workers/Scheduler.php
@@ -232,6 +232,9 @@ class Scheduler {
 
   public function createNotificationHistory($newsletterId) {
     $newsletter = Newsletter::findOne($newsletterId);
+    if (!$newsletter instanceof Newsletter) {
+      return false;
+    }
     $notificationHistory = $newsletter->createNotificationHistory();
     return ($notificationHistory->getErrors() === false) ?
       $notificationHistory :