diff --git a/phpseclib/Crypt/Base.php b/phpseclib/Crypt/Base.php
index d4ce09f9..602f097c 100644
--- a/phpseclib/Crypt/Base.php
+++ b/phpseclib/Crypt/Base.php
@@ -2079,7 +2079,9 @@ abstract class Base
     function _increment_str(&$var)
     {
         if (function_exists('sodium_increment')) {
+            $var = strrev($var);
             sodium_increment($var);
+            $var = strrev($var);
             return;
         }