diff --git a/change_log.txt b/change_log.txt
index b9778c3e..c0bf6609 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -1,6 +1,7 @@
 ===== trunk  =====
 05.10.2011
 - bugfix of problem introduced with r4342 by replacing strlen() with isset()
+- add environment configuration issue with mbstring.func_overload Smarty cannot compensate for (Issue #45)
 
 04.10.2011
 - bugfix assign() in plugins called in subtemplates did change value also in parent template
diff --git a/libs/Smarty.class.php b/libs/Smarty.class.php
index 8060f3b9..10affa91 100644
--- a/libs/Smarty.class.php
+++ b/libs/Smarty.class.php
@@ -57,6 +57,9 @@ if (!defined('SMARTY_PLUGINS_DIR')) {
     define('SMARTY_PLUGINS_DIR', SMARTY_DIR . 'plugins' . DS);
 }
 if (!defined('SMARTY_MBSTRING')) {
+    if (ini_get('mbstring.func_overload') & 2) {
+        throw new SmartyException("mbstring.func_overload is active which breaks Smarty's compiler.");
+    }
     define('SMARTY_MBSTRING', function_exists('mb_strlen'));
 }
 if (!defined('SMARTY_RESOURCE_CHAR_SET')) {