diff --git a/lib/plugins/helper/gravatar.js b/lib/plugins/helper/gravatar.js
index e0ca261dcb..6ebaea5410 100644
--- a/lib/plugins/helper/gravatar.js
+++ b/lib/plugins/helper/gravatar.js
@@ -12,7 +12,7 @@ function gravatarHelper(email, options) {
     options = {s: options};
   }
 
-  var str = 'http://www.gravatar.com/avatar/' + md5(email.toLowerCase());
+  var str = 'https://www.gravatar.com/avatar/' + md5(email.toLowerCase());
   var qs = querystring.stringify(options);
 
   if (qs) str += '?' + qs;