diff --git a/functions.php b/functions.php
index 71231b8..a5b943b 100644
--- a/functions.php
+++ b/functions.php
@@ -1,6 +1,8 @@
 <?php
 if (!defined('__TYPECHO_ROOT_DIR__')) exit;
 
+define('__TYPECHO_GRAVATAR_PREFIX__', 'https://cdn.v2ex.com/gravatar/');
+
 function themeConfig($form) {
     echo $siteUrl;