diff --git a/Helper/Helper.php b/Helper/Helper.php
index 0ddddf6bc..0521aaf7d 100644
--- a/Helper/Helper.php
+++ b/Helper/Helper.php
@@ -47,6 +47,8 @@ public function getHelperSet()
      */
     public static function strlen($string)
     {
+        $string = (string) $string;
+
         if (false === $encoding = mb_detect_encoding($string, null, true)) {
             return \strlen($string);
         }
@@ -65,6 +67,8 @@ public static function strlen($string)
      */
     public static function substr($string, $from, $length = null)
     {
+        $string = (string) $string;
+
         if (false === $encoding = mb_detect_encoding($string, null, true)) {
             return substr($string, $from, $length);
         }