diff --git a/modules/user/user.module b/modules/user/user.module
index 94ecaa2..9a35676 100644
--- a/modules/user/user.module
+++ b/modules/user/user.module
@@ -3628,6 +3628,9 @@ function user_block_user_action(&$entity, $context = array()) {
  * field instance' form.
  */
 function user_form_field_ui_field_edit_form_alter(&$form, &$form_state, $form_id) {
+  if (!empty($form['#field']['locked'])) {
+    return;
+  }
   $instance = $form['#instance'];
 
   if ($instance['entity_type'] == 'user') {