diff --git a/app/code/core/Mage/Adminhtml/Block/System/Config/Form/Field.php b/app/code/core/Mage/Adminhtml/Block/System/Config/Form/Field.php
index 45d035579eb..b716e9ebec5 100644
--- a/app/code/core/Mage/Adminhtml/Block/System/Config/Form/Field.php
+++ b/app/code/core/Mage/Adminhtml/Block/System/Config/Form/Field.php
@@ -42,7 +42,7 @@ public function render(Varien_Data_Form_Element_Abstract $element)
         $isMultiple = $element->getExtType() === 'multiple';
 
         // replace [value] with [inherit]
-        $namePrefix = preg_replace('#\[value\](\[\])?$#', '', $element->getName());
+        $namePrefix = preg_replace('#\[value\](\[\])?$#', '', (string) $element->getName());
 
         $options = $element->getValues();