diff --git a/CRM/Utils/System/Base.php b/CRM/Utils/System/Base.php
index 336d07568abf..d2e5fa93bbe6 100644
--- a/CRM/Utils/System/Base.php
+++ b/CRM/Utils/System/Base.php
@@ -729,7 +729,7 @@ public function getCiviSourceStorage() {
       }
     }
     else {
-      $userFrameworkResourceURL = NULL;
+      $userFrameworkResourceURL = '';
     }
 
     return [