diff --git a/classes/persistents/message.php b/classes/persistents/message.php
index 3d6a480..59fb2fb 100644
--- a/classes/persistents/message.php
+++ b/classes/persistents/message.php
@@ -242,17 +242,17 @@ public function get_message_recipient_users($status = 'all', $userproperties = '
      */
     public function get_broadcast_draft_recipient_filter() {
         if ($this->get_message_scope() !== 'broadcast') {
-            return '';
+            return array();
         }
 
         $recipients = $this->get_message_draft_recipients();
 
         if (!$recip = reset($recipients)) {
-            return '';
+            return array();
         }
 
         if (!$filter = $recip->get('recipient_filter')) {
-            return '';
+            return array();
         }
 
         return @unserialize($filter);