diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index d6e3bebd0e8ea0ea10fd846cf224162b0ef87020..4d1dc27f7176ed8fa7961ad635478808e88f902f 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -221,9 +221,9 @@ public function getForm($form_arg) {
   /**
    * {@inheritdoc}
    */
-  public function buildForm($form_id, FormStateInterface &$form_state) {
+  public function buildForm($form_arg, FormStateInterface &$form_state) {
     // Ensure the form ID is prepared.
-    $form_id = $this->getFormId($form_id, $form_state);
+    $form_id = $this->getFormId($form_arg, $form_state);
 
     $request = $this->requestStack->getCurrentRequest();
 
diff --git a/core/lib/Drupal/Core/Form/FormBuilderInterface.php b/core/lib/Drupal/Core/Form/FormBuilderInterface.php
index ca794379dbb5872612a830bfcb983a48f38564ac..6b6ed83046b0d27b43713a54c960f8207ae70288 100644
--- a/core/lib/Drupal/Core/Form/FormBuilderInterface.php
+++ b/core/lib/Drupal/Core/Form/FormBuilderInterface.php
@@ -68,7 +68,7 @@ public function getForm($form_arg);
    * previous page load. The form is then passed on for processing, validation,
    * and submission if there is proper input.
    *
-   * @param \Drupal\Core\Form\FormInterface|string $form_id
+   * @param \Drupal\Core\Form\FormInterface|string $form_arg
    *   The value must be one of the following:
    *   - The name of a class that implements \Drupal\Core\Form\FormInterface.
    *   - An instance of a class that implements \Drupal\Core\Form\FormInterface.
@@ -89,7 +89,7 @@ public function getForm($form_arg);
    *
    * @see self::redirectForm()
    */
-  public function buildForm($form_id, FormStateInterface &$form_state);
+  public function buildForm($form_arg, FormStateInterface &$form_state);
 
   /**
    * Constructs a new $form from the information in $form_state.