diff --git a/docs/NEWS b/docs/NEWS
index d7ad7e52..5321c036 100644
--- a/docs/NEWS
+++ b/docs/NEWS
@@ -3,6 +3,9 @@
 Version 1.2 ()
 ------------------------------------------------------------------------
 
+    * Stricter mbstring-extension check for special charsets like czech,
+      thanks to mila
+
     * Upgraded DB-scheme to allow longer author usernames
 
     * Improved Spamblock plugin to allow filtering email addresses
diff --git a/include/lang.inc.php b/include/lang.inc.php
index e2302a11..b7d7c93b 100644
--- a/include/lang.inc.php
+++ b/include/lang.inc.php
@@ -59,7 +59,7 @@ if (!defined('serendipity_MB_LOADED') && defined('serendipity_LANG_LOADED')) {
         static $mbstring = null;
 
         if (is_null($mbstring)) {
-            $mbstring = (extension_loaded('mbstring') ? 1 : 0);
+            $mbstring = (extension_loaded('mbstring') && @mb_internal_encoding(LANG_CHARSET) ? 1 : 0);
             if ($mbstring === 1) {
                 if (function_exists('mb_strtoupper')) {
                     $mbstring = 2;