diff --git a/core/core.services.yml b/core/core.services.yml
index d050591..419beaa 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -125,7 +125,7 @@ services:
     arguments: ['@form_validator', '@module_handler', '@keyvalue.expirable', '@event_dispatcher', '@url_generator', '@request_stack', '@?csrf_token', '@?http_kernel']
   form_validator:
     class: Drupal\Core\Form\FormValidator
-    arguments: ['@request_stack', '@?csrf_token']
+    arguments: ['@request_stack', '@string_translation', '@csrf_token']
   keyvalue:
     class: Drupal\Core\KeyValueStore\KeyValueFactory
     arguments: ['@service_container', '@settings']
diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index c1fa894..3efa1f2 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -555,6 +555,7 @@ public function processForm($form_id, &$form, &$form_state) {
         $this->drupalStaticReset('drupal_html_id');
       }
 
+      // @todo Move into a dedicated class in https://drupal.org/node/2257835.
       if ($form_state['submitted'] && !$this->getAnyErrors() && !$form_state['rebuild']) {
         // Execute form submit handlers.
         $this->executeSubmitHandlers($form, $form_state);
diff --git a/core/lib/Drupal/Core/Form/FormValidator.php b/core/lib/Drupal/Core/Form/FormValidator.php
index 2cb1141..9e73738 100644
--- a/core/lib/Drupal/Core/Form/FormValidator.php
+++ b/core/lib/Drupal/Core/Form/FormValidator.php
@@ -12,7 +12,7 @@
 use Drupal\Core\Access\CsrfTokenGenerator;
 use Drupal\Core\Render\Element;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
-use Drupal\Core\Form\OptGroup;
+use Drupal\Core\StringTranslation\TranslationInterface;
 use Symfony\Component\HttpFoundation\RequestStack;
 
 /**
@@ -41,11 +41,14 @@ class FormValidator implements FormValidatorInterface {
    *
    * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
    *   The request stack.
+   * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
+   *   The string translation service.
    * @param \Drupal\Core\Access\CsrfTokenGenerator $csrf_token
    *   The CSRF token generator.
    */
-  public function __construct(RequestStack $request_stack, CsrfTokenGenerator $csrf_token = NULL) {
+  public function __construct(RequestStack $request_stack, TranslationInterface $string_translation, CsrfTokenGenerator $csrf_token) {
     $this->requestStack = $request_stack;
+    $this->stringTranslation = $string_translation;
     $this->csrfToken = $csrf_token;
   }
 
diff --git a/core/tests/Drupal/Tests/Core/Form/FormValidatorTest.php b/core/tests/Drupal/Tests/Core/Form/FormValidatorTest.php
index 81bfeb8..efb06c4 100644
--- a/core/tests/Drupal/Tests/Core/Form/FormValidatorTest.php
+++ b/core/tests/Drupal/Tests/Core/Form/FormValidatorTest.php
@@ -125,15 +125,10 @@ public function testValidateInvalidFormToken() {
       ->will($this->returnValue(FALSE));
 
     $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
-      ->setConstructorArgs(array($request_stack, $csrf_token))
-      ->setMethods(array('setErrorByName', 't', 'doValidateForm'))
+      ->setConstructorArgs(array($request_stack, $this->getStringTranslationStub(), $csrf_token))
+      ->setMethods(array('setErrorByName', 'doValidateForm'))
       ->getMock();
     $form_validator->expects($this->once())
-      ->method('t')
-      ->will($this->returnCallback(function ($string, $args) {
-        return String::format($string, $args);
-      }));
-    $form_validator->expects($this->once())
       ->method('setErrorByName')
       ->with('form_token', $this->isType('array'), 'The form has become outdated. Copy any unsaved work in the form below and then <a href="/test/example?foo=bar">reload this page</a>.');
     $form_validator->expects($this->never())
@@ -159,7 +154,7 @@ public function testValidateValidFormToken() {
       ->will($this->returnValue(TRUE));
 
     $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
-      ->setConstructorArgs(array($request_stack, $csrf_token))
+      ->setConstructorArgs(array($request_stack, $this->getStringTranslationStub(), $csrf_token))
       ->setMethods(array('setErrorByName', 'doValidateForm'))
       ->getMock();
     $form_validator->expects($this->never())
@@ -237,8 +232,11 @@ public function testSetErrorByName($limit_validation_errors, $expected_errors, $
     $request_stack = new RequestStack();
     $request = new Request();
     $request_stack->push($request);
+    $csrf_token = $this->getMockBuilder('Drupal\Core\Access\CsrfTokenGenerator')
+      ->disableOriginalConstructor()
+      ->getMock();
     $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
-      ->setConstructorArgs(array($request_stack))
+      ->setConstructorArgs(array($request_stack, $this->getStringTranslationStub(), $csrf_token))
       ->setMethods(array('drupalSetMessage'))
       ->getMock();
     $form_validator->expects($set_message ? $this->once() : $this->never())
@@ -273,8 +271,11 @@ public function testSetElementErrorsFromFormState() {
     $request_stack = new RequestStack();
     $request = new Request();
     $request_stack->push($request);
+    $csrf_token = $this->getMockBuilder('Drupal\Core\Access\CsrfTokenGenerator')
+      ->disableOriginalConstructor()
+      ->getMock();
     $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
-      ->setConstructorArgs(array($request_stack))
+      ->setConstructorArgs(array($request_stack, $this->getStringTranslationStub(), $csrf_token))
       ->setMethods(array('drupalSetMessage'))
       ->getMock();
 
@@ -424,17 +425,15 @@ public function testExecuteValidateHandlers() {
    * @dataProvider providerTestRequiredErrorMessage
    */
   public function testRequiredErrorMessage($element, $expected_message) {
-    $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
+    $csrf_token = $this->getMockBuilder('Drupal\Core\Access\CsrfTokenGenerator')
       ->disableOriginalConstructor()
-      ->setMethods(array('executeValidateHandlers', 't', 'setErrorByName'))
+      ->getMock();
+    $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
+      ->setConstructorArgs(array(new RequestStack(), $this->getStringTranslationStub(), $csrf_token))
+      ->setMethods(array('executeValidateHandlers', 'setErrorByName'))
       ->getMock();
     $form_validator->expects($this->once())
       ->method('executeValidateHandlers');
-    $form_validator->expects($this->any())
-      ->method('t')
-      ->will($this->returnCallback(function ($string, $args) {
-        return String::format($string, $args);
-      }));
     $form_validator->expects($this->once())
       ->method('setErrorByName')
       ->with('test', $this->isType('array'), $expected_message);
@@ -477,15 +476,10 @@ public function providerTestRequiredErrorMessage() {
   public function testElementValidate() {
     $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
       ->disableOriginalConstructor()
-      ->setMethods(array('executeValidateHandlers', 't', 'setErrorByName'))
+      ->setMethods(array('executeValidateHandlers', 'setErrorByName'))
       ->getMock();
     $form_validator->expects($this->once())
       ->method('executeValidateHandlers');
-    $form_validator->expects($this->any())
-      ->method('t')
-      ->will($this->returnCallback(function ($string, $args) {
-        return String::format($string, $args);
-      }));
     $mock = $this->getMock('stdClass', array('element_validate'));
     $mock->expects($this->once())
       ->method('element_validate')
@@ -508,15 +502,13 @@ public function testElementValidate() {
    * @dataProvider providerTestPerformRequiredValidation
    */
   public function testPerformRequiredValidation($element, $expected_message, $call_watchdog) {
-    $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
+    $csrf_token = $this->getMockBuilder('Drupal\Core\Access\CsrfTokenGenerator')
       ->disableOriginalConstructor()
-      ->setMethods(array('t', 'setErrorByName', 'watchdog'))
       ->getMock();
-    $form_validator->expects($this->any())
-      ->method('t')
-      ->will($this->returnCallback(function ($string, $args) {
-        return String::format($string, $args);
-      }));
+    $form_validator = $this->getMockBuilder('Drupal\Core\Form\FormValidator')
+      ->setConstructorArgs(array(new RequestStack(), $this->getStringTranslationStub(), $csrf_token))
+      ->setMethods(array('setErrorByName', 'watchdog'))
+      ->getMock();
     $form_validator->expects($this->once())
       ->method('setErrorByName')
       ->with('test', $this->isType('array'), $expected_message);