diff --git a/toolkit/components/osfile/osfile_async_front.jsm b/toolkit/components/osfile/osfile_async_front.jsm
index 2bd02d6abd5..d2d51bea82e 100644
--- a/toolkit/components/osfile/osfile_async_front.jsm
+++ b/toolkit/components/osfile/osfile_async_front.jsm
@@ -718,6 +718,9 @@ let DirectoryIterator = function DirectoryIterator(path, options) {
   this._isClosed = false;
 };
 DirectoryIterator.prototype = {
+  iterator: function () this,
+  __iterator__: function () this,
+
   /**
    * Determine whether the directory exists.
    *