diff --git a/lib/Pear_CHAP.php b/lib/Pear_CHAP.php
index aa6878e..0531cf5 100644
--- a/lib/Pear_CHAP.php
+++ b/lib/Pear_CHAP.php
@@ -240,8 +240,8 @@ public function str2unicode($str)
     {
         $uni = '';
         $str = (string) $str;
-        for ($i = 0; $i < strlen($str); $i++) {
-            $a = ord($str{$i}) << 8;
+        for ($i = 0; $i < mb_strlen($str); $i++) {
+            $a = mb_ord(mb_substr($str,$i,1)) << 8;
             $uni .= sprintf("%X", $a);
         }
         return pack('H*', $uni);