diff --git a/templates/index.html b/templates/index.html
index 80aafde91..0d5f40233 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -60,7 +60,7 @@
             <!--<button type="button" class="btn btn-default navbar-btn">Sign in</button>-->
 
             <a href="javascript:void(0)" class="dropdown-toggle user-dropdown" data-toggle="dropdown">
-              <img src="http://www.gravatar.com/avatar/{{ user.gravatar }}?s=32&d=identicon" />
+              <img src="//www.gravatar.com/avatar/{{ user.gravatar }}?s=32&d=identicon" />
               {{ user.username }}
               <b class="caret"></b>
             </a>