diff --git a/core/modules/rest/rest.module b/core/modules/rest/rest.module
index 5e2cf86..4f2c24d 100644
--- a/core/modules/rest/rest.module
+++ b/core/modules/rest/rest.module
@@ -39,5 +39,9 @@ function rest_help($path, $arg) {
  * Implements hook_entity_info_alter().
  */
 function rest_entity_info_alter(&$entity_info) {
-  $entity_info['file']['controllers']['access'] = 'Drupal\rest\FileAccessController';
+  if (isset($entity_info['file'])) {
+    $controllers = $entity_info['file']->get('controllers');
+    $controllers['access'] = 'Drupal\\rest\\FileAccessController';
+    $entity_info['file']->set('controllers', $controllers);
+  }
 }