diff --git a/includes/admin.form.inc b/includes/admin.form.inc
index c1ec317..0e8c507 100644
--- a/includes/admin.form.inc
+++ b/includes/admin.form.inc
@@ -88,7 +88,7 @@ function islandora_audio_admin(array $form, array &$form_state) {
  *   The element to render as part the ajax callback.
  */
 function islandora_audio_admin_form_lame_ajax_callback(array $form, array $form_state) {
-  return $form['islandora_lame_url'];
+  return $form['derivatives']['islandora_lame_url'];
 }
 
 /**