diff --git a/lib/javascript-static.js b/lib/javascript-static.js
index c00a0ef5cbc..df59cd7323e 100644
--- a/lib/javascript-static.js
+++ b/lib/javascript-static.js
@@ -667,34 +667,25 @@ M.util.js_pending = function(uniqid) {
     return M.util.pending_js.length;
 };
 
+// Start this asap.
+M.util.js_pending('init');
+
 /**
  * Register listeners for Y.io start/end so we can wait for them in behat.
  */
-M.util.js_watch_io = function() {
-    YUI.add('moodle-core-io', function(Y) {
-        Y.on('io:start', function(id) {
-            M.util.js_pending('io:' + id);
-        });
-        Y.on('io:end', function(id) {
-            M.util.js_complete('io:' + id);
-        });
+YUI.add('moodle-core-io', function(Y) {
+    Y.on('io:start', function(id) {
+        M.util.js_pending('io:' + id);
     });
-    YUI.applyConfig({
-        modules: {
-            'moodle-core-io': {
-                after: ['io-base']
-            },
-            'io-base': {
-                requires: ['moodle-core-io'],
-            }
-        }
+    Y.on('io:end', function(id) {
+        M.util.js_complete('io:' + id);
     });
-
-};
-
-// Start this asap.
-M.util.js_pending('init');
-M.util.js_watch_io();
+}, '@VERSION@', {
+    condition: {
+        trigger: 'io-base',
+        when: 'after'
+    }
+});
 
 /**
  * Unregister any long running javascript code by unique identifier.