diff --git a/libraries/Util.php b/libraries/Util.php
index ba7e8980cf..64dd51fd92 100644
--- a/libraries/Util.php
+++ b/libraries/Util.php
@@ -4883,7 +4883,7 @@ class Util
     {
         $result = '';
         if (class_exists('phpseclib\\Crypt\\Random')) {
-            $random_func = 'phpseclib\\Crypt\\Random::string';
+            $random_func = array('phpseclib\\Crypt\\Random', 'string');
         } else {
             $random_func = 'openssl_random_pseudo_bytes';
         }