diff --git a/workbench_access.module b/workbench_access.module
index f282249..912f532 100644
--- a/workbench_access.module
+++ b/workbench_access.module
@@ -44,6 +44,11 @@ function workbench_access_form_node_form_alter(&$form, FormStateInterface $form_
     $node = $form_state->getFormObject()->getEntity();
     $field = $scheme->fields('node', $node->bundle());
     $account = \Drupal::currentUser();
+
+    if (empty($field)) {
+      return;
+    }
+
     // If the user cannot access the form element or is a superuser, ignore.
     if (!empty($form[$field]['#access']) && !$account->hasPermission('bypass workbench access')) {
       $form[$field] = $scheme->alterOptions($form[$field], $manager);