Don't rely on d.head, use d.documentElement instead.

4chan_x.user.js

@@ -1812,6 +1812,7 @@
           textContent: "window.addEventListener('message'," + code + ",false)"
         });
         ready = function() {
+          $.add(d.documentElement, script);
           if (location.hostname === 'sys.4chan.org') {
             qr.message.send({
               req: 'status',
@@ -1821,14 +1822,10 @@
           return $.rm(script);
         };
         if (d.documentElement) {
-          $.add(d.documentElement, script);
-          ready();
-          return;
-        }
-        return $.ready(function() {
-          $.add(d.head, script);
           return ready();
-        });
+        } else {
+          return $.ready(ready);
+        }
       },
       send: function(data) {
         data.changeContext = true;

script.coffee

@@ -1400,18 +1400,15 @@ qr =
           parent.postMessage data, '*'
       script = $.el 'script', textContent: "window.addEventListener('message',#{code},false)"
       ready = ->
+        $.add d.documentElement, script
         if location.hostname is 'sys.4chan.org'
           qr.message.send req: 'status', ready: true
         $.rm script
       # Chrome can access the documentElement on document-start
       if d.documentElement
-        $.add d.documentElement, script
         ready()
-        return
       # other browsers will have to wait
-      $.ready ->
+      else $.ready ready
-        $.add d.head, script
-        ready()
     send: (data) ->
       data.changeContext = true
       data.qr            = true