diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index 435437c..2c5bd56 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -19,7 +19,6 @@
 use Drupal\Core\Form\Exception\BrokenPostRequestException;
 use Drupal\Core\Render\Element;
 use Drupal\Core\Render\ElementInfoManagerInterface;
-use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\Core\Theme\ThemeManagerInterface;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
@@ -32,8 +31,6 @@
  */
 class FormBuilder implements FormBuilderInterface, FormValidatorInterface, FormSubmitterInterface, FormCacheInterface {
 
-  use StringTranslationTrait;
-
   /**
    * The module handler.
    *
@@ -767,6 +764,13 @@ protected function buildFormAction() {
   /**
    * {@inheritdoc}
    */
+  public function setInvalidTokenError(FormStateInterface $form_state) {
+    $this->formValidator->setInvalidTokenError($form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function validateForm($form_id, &$form, FormStateInterface &$form_state) {
     $this->formValidator->validateForm($form_id, $form, $form_state);
   }
@@ -846,10 +850,7 @@ public function doBuildForm($form_id, &$element, FormStateInterface &$form_state
           if (empty($input['form_token']) || !$this->csrfToken->validate($input['form_token'], $element['#token'])) {
             // Set an early form error to block certain input processing since
             // that opens the door for CSRF vulnerabilities.
-            $url = $this->requestStack->getCurrentRequest()->getRequestUri();
-
-            // Setting this error will cause the form to fail validation.
-            $form_state->setErrorByName('form_token', $this->t('The form has become outdated. Copy any unsaved work in the form below and then <a href="@link">reload this page</a>.', array('@link' => $url)));
+            $this->setInvalidTokenError($form_state);
 
             // This value is checked in self::handleInputElement().
             $form_state->setInvalidToken(TRUE);
diff --git a/core/lib/Drupal/Core/Form/FormValidator.php b/core/lib/Drupal/Core/Form/FormValidator.php
index f3e36aa..10678e3 100644
--- a/core/lib/Drupal/Core/Form/FormValidator.php
+++ b/core/lib/Drupal/Core/Form/FormValidator.php
@@ -110,10 +110,7 @@ public function validateForm($form_id, &$form, FormStateInterface &$form_state)
     // code.
     if (isset($form['#token'])) {
       if (!$this->csrfToken->validate($form_state->getValue('form_token'), $form['#token']) || $form_state->hasInvalidToken()) {
-        $url = $this->requestStack->getCurrentRequest()->getRequestUri();
-
-        // Setting this error will cause the form to fail validation.
-        $form_state->setErrorByName('form_token', $this->t('The form has become outdated. Copy any unsaved work in the form below and then <a href="@link">reload this page</a>.', array('@link' => $url)));
+        $this->setInvalidTokenError($form_state);
 
         // Stop here and don't run any further validation handlers, because they
         // could invoke non-safe operations which opens the door for CSRF
@@ -130,6 +127,16 @@ public function validateForm($form_id, &$form, FormStateInterface &$form_state)
   }
 
   /**
+   * {@inheritdoc}
+   */
+  public function setInvalidTokenError(FormStateInterface $form_state) {
+    $url = $this->requestStack->getCurrentRequest()->getRequestUri();
+
+    // Setting this error will cause the form to fail validation.
+    $form_state->setErrorByName('form_token', $this->t('The form has become outdated. Copy any unsaved work in the form below and then <a href="@link">reload this page</a>.', array('@link' => $url)));
+  }
+
+  /**
    * Handles validation errors for forms with limited validation.
    *
    * If validation errors are limited then remove any non validated form values,
diff --git a/core/lib/Drupal/Core/Form/FormValidatorInterface.php b/core/lib/Drupal/Core/Form/FormValidatorInterface.php
index 6f1cc52..d2c8945 100644
--- a/core/lib/Drupal/Core/Form/FormValidatorInterface.php
+++ b/core/lib/Drupal/Core/Form/FormValidatorInterface.php
@@ -54,4 +54,14 @@ public function executeValidateHandlers(&$form, FormStateInterface &$form_state)
    */
   public function validateForm($form_id, &$form, FormStateInterface &$form_state);
 
+  /**
+   * Sets a form_token error on the given form state.
+   *
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   *
+   * @return $this
+   */
+  public function setInvalidTokenError(FormStateInterface $form_state);
+
 }