diff --git a/phpseclib/Common/Functions/Strings.php b/phpseclib/Common/Functions/Strings.php
index 72cca8a9..10314aed 100644
--- a/phpseclib/Common/Functions/Strings.php
+++ b/phpseclib/Common/Functions/Strings.php
@@ -379,8 +379,10 @@ abstract class Strings
     public static function increment_str(&$var)
     {
         if (function_exists('sodium_increment')) {
+            $var = strrev($var);
             sodium_increment($var);
-            return;
+            $var = strrev($var);
+            return $var;
         }
 
         for ($i = 4; $i <= strlen($var); $i+= 4) {