diff --git a/src/General/$.coffee b/src/General/$.coffee
index 975fa7277..8e982e16d 100644
--- a/src/General/$.coffee
+++ b/src/General/$.coffee
@@ -55,6 +55,8 @@ $.ajax = do ->
     new Notice 'error', message, 30, -> delete blockedURLs[url]
   (url, options={}, extra={}) ->
     {type, whenModified, upCallbacks, form} = extra
+    # XXX https://forums.lanik.us/viewtopic.php?f=64&t=24173&p=78310
+    url = url.replace /^\/\/a\.4cdn\.org\/adv\//, '//a.4cdn.org//adv/'
     r = new XMLHttpRequest()
     type or= form and 'post' or 'get'
     try