diff --git a/modules/file/file.module b/modules/file/file.module
index ed16536..ca5d7c2 100644
--- a/modules/file/file.module
+++ b/modules/file/file.module
@@ -458,10 +458,19 @@ function file_managed_file_process($element, &$form_state, $form) {
   // Add the extension list to the page as JavaScript settings.
   if (isset($element['#upload_validators']['file_validate_extensions'][0])) {
     $extension_list = implode(',', array_filter(explode(' ', $element['#upload_validators']['file_validate_extensions'][0])));
+    list($upload_id, $count) = array_pad(explode('--', $element['#id']), 2, NULL);
+
+    if ($count) {
+      $selector = '#' . $upload_id . '-upload--' . $count;
+    }
+    else {
+      $selector = '#' . $upload_id . '-upload';
+    }
+
     $element['upload']['#attached']['js'] = array(
       array(
         'type' => 'setting',
-        'data' => array('file' => array('elements' => array('#' . $element['#id'] . '-upload' => $extension_list)))
+        'data' => array('file' => array('elements' => array($selector => $extension_list)))
       )
     );
   }