diff --git a/lib/Varien/Object.php b/lib/Varien/Object.php
index bfd0f11bcff..0ddf7a65caa 100644
--- a/lib/Varien/Object.php
+++ b/lib/Varien/Object.php
@@ -591,7 +591,7 @@ public function toString($format = '')
         } else {
             preg_match_all('/\{\{([a-z0-9_]+)\}\}/is', $format, $matches);
             foreach ($matches[1] as $var) {
-                $format = str_replace('{{' . $var . '}}', $this->getData($var), $format);
+                $format = str_replace('{{' . $var . '}}', (string) $this->getData($var), $format);
             }
             $str = $format;
         }