diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
index 54a5f0e..6016fce 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
@@ -166,6 +166,20 @@ function testLanguageList() {
     // We need raw here because %language and %langcode will add HTML.
     $t_args = array('%language' => 'English', '%langcode' => 'en');
     $this->assertRaw(t('The %language (%langcode) language has been removed.', $t_args), 'The English language has been removed.');
+
+    // Try to add a language with an invalid name.
+    // Code for the language.
+    $langcode = 'xx_broken';
+    // The invalid name for the language.
+    $name = '<br />' . $this->randomName(16);
+    $edit_broken = array(
+     'predefined_langcode' => 'custom',
+     'langcode' => $langcode,
+     'name' => $name,
+     'direction' => '0',
+    );
+    $this->drupalPost('admin/config/regional/language/add', $edit_broken, t('Add custom language'));
+    $this->assertRaw(t('%field cannot contain any markup.', array('%field' => t('Language name'))), 'Markup in language name not allowed.');
   }
 
   /**