diff --git a/app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Serialized.php b/app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Serialized.php
index b9c829e3abc..e3eceb015bb 100644
--- a/app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Serialized.php
+++ b/app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Serialized.php
@@ -34,7 +34,7 @@ protected function _afterLoad()
             if (!empty($serializedValue)) {
                 try {
                     $unserializedValue = Mage::helper('core/unserializeArray')
-                        ->unserialize($serializedValue);
+                        ->unserialize((string)$serializedValue);
                 } catch (Exception $e) {
                     Mage::logException($e);
                 }