diff --git a/change_log.txt b/change_log.txt
index e5a31f96..e663dea3 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -1,7 +1,10 @@
  ===== 3.1.25-dev===== (xx.xx.2015)
+ 13.06.2015
+  - bugfix a custom cache resource using smarty_cachereource_keyvaluestore.php did fail if php.ini mbstring.func_overload = 2 (forum topic 25568)
+
  11.06.2015
   - bugfix the lexer could hang on very large quoted strings (forum topic 25570)
-  
+
  08.06.2015
   - bugfix using {$foo} as array index like $bar.{$foo} or in double quoted string like "some {$foo} thing" failed https://github.com/smarty-php/smarty/issues/49
 
diff --git a/libs/Smarty.class.php b/libs/Smarty.class.php
index 57410a69..11ebe460 100644
--- a/libs/Smarty.class.php
+++ b/libs/Smarty.class.php
@@ -111,7 +111,7 @@ class Smarty extends Smarty_Internal_TemplateBase
     /**
      * smarty version
      */
-    const SMARTY_VERSION = '3.1.25-dev/5';
+    const SMARTY_VERSION = '3.1.25-dev/6';
 
     /**
      * define variable scopes
diff --git a/libs/sysplugins/smarty_cacheresource_keyvaluestore.php b/libs/sysplugins/smarty_cacheresource_keyvaluestore.php
index c1c0f3fe..507608e4 100644
--- a/libs/sysplugins/smarty_cacheresource_keyvaluestore.php
+++ b/libs/sysplugins/smarty_cacheresource_keyvaluestore.php
@@ -298,8 +298,8 @@ abstract class Smarty_CacheResource_KeyValueStore extends Smarty_CacheResource
      */
     protected function getMetaTimestamp(&$content)
     {
-        $s = unpack("N", substr($content, 0, 4));
-        $m = unpack("N", substr($content, 4, 4));
+        $s = unpack("N", $content[0] . $content[1] . $content[2] . $content[3]);
+        $m = unpack("N", $content[4] . $content[5] . $content[6] . $content[7]);
         $content = substr($content, 8);
 
         return $s[1] + ($m[1] / 100000000);