diff --git a/core/core.api.php b/core/core.api.php
index 7b90ae21f7bb0b5b0d077100b556fba5be5d5c93..639e55dd97803ce11e83119591fc6390168d4092 100644
--- a/core/core.api.php
+++ b/core/core.api.php
@@ -1692,7 +1692,11 @@
  *     // Create a $form API array.
  *     $form['phone_number'] = array(
  *       '#type' => 'tel',
- *       '#title' => $this->t('Your phone number')
+ *       '#title' => $this->t('Your phone number'),
+ *     );
+ *     $form['save'] = array(
+ *       '#type' => 'submit',
+ *       '#value' => $this->t('Save'),
  *     );
  *     return $form;
  *   }