diff --git a/js/ui/environment.js b/js/ui/environment.js
index 4a1231402..44a92db36 100644
--- a/js/ui/environment.js
+++ b/js/ui/environment.js
@@ -285,6 +285,11 @@ function init() {
         _easeActorProperty(this, 'value', target, params);
     };
 
+    Clutter.Actor.prototype.iterate_children = function* () {
+        for (let c = this.get_first_child(); c; c = c.get_next_sibling())
+            yield c;
+    };
+
     Clutter.Actor.prototype.toString = function () {
         return St.describe_actor(this);
     };