diff --git a/htdocs/includes/symfony/var-dumper/Cloner/VarCloner.php b/htdocs/includes/symfony/var-dumper/Cloner/VarCloner.php
index 98d6e9e51c1..20cc8d08354 100644
--- a/htdocs/includes/symfony/var-dumper/Cloner/VarCloner.php
+++ b/htdocs/includes/symfony/var-dumper/Cloner/VarCloner.php
@@ -291,7 +291,7 @@ class VarCloner extends AbstractCloner
             if (!empty($frame['line'])) {
                 ob_start();
                 debug_zval_dump($obj);
-                self::$hashMask = substr(ob_get_clean(), 17);
+                self::$hashMask = strlen(substr(ob_get_clean(), 17));
             }
         }