diff --git a/core/modules/config/src/Tests/LanguageNegotiationFormOverrideTest.php b/core/modules/config/src/Tests/LanguageNegotiationFormOverrideTest.php
new file mode 100644
index 0000000..b5289cb
--- /dev/null
+++ b/core/modules/config/src/Tests/LanguageNegotiationFormOverrideTest.php
@@ -0,0 +1,63 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\config\Tests\LanguageNegotiationFormOverrideTest.
+ */
+
+namespace Drupal\config\Tests;
+
+use Drupal\simpletest\WebTestBase;
+
+/**
+ * Tests language-negotiation overrides are not on language-negotiation form.
+ *
+ * @group config
+ * @see \Drupal\Core\Form\ConfigFormBase
+ */
+class LanguageNegotiationFormOverrideTest extends WebTestBase {
+
+  public static $modules = array('language', 'locale');
+
+  /**
+   * Tests that overrides do not affect language-negotiation form values.
+   */
+  public function testFormWithOverride() {
+    $this->drupalLogin($this->rootUser);
+    $overridden_value_en = 'whatever';
+    $overridden_value_es = 'loquesea';
+
+    // Set up an override.
+    $settings['config']['language.negotiation']['url']['prefixes'] = (object) array(
+      'value' => array('en' => $overridden_value_en, 'es' => $overridden_value_es),
+      'required' => TRUE,
+    );
+    $this->writeSettings($settings);
+
+    // Add predefined language.
+    $edit = array(
+      'predefined_langcode' => 'es',
+    );
+    $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add language'));
+
+    // Overridden string for language-negotiation should not exist in the form.
+    $this->drupalGet('admin/config/regional/language/detection/url');
+
+    // The language-negotiation form should be found.
+    $this->assertText('Path prefix configuration', 'Language-negotiation form found for English.');
+
+    // The English override should not be found.
+    $this->assertNoFieldByName('prefix[en]', $overridden_value_en, 'Language-negotiation config override not found in English.');
+
+    // Now check the Spanish version of the page for the same thing.
+    $this->drupalGet($overridden_value_es . '/admin/config/regional/language/detection/url');
+
+    // The language-negotiation form should be found.
+    $this->assertText('Path prefix configuration', 'Language-negotiation form found for Spanish using the overridden prefix.');
+
+    // The Spanish override should not be found.
+    $this->assertNoFieldByName('prefix[es]', $overridden_value_es, 'Language-negotiation config override not found in Spanish.');
+
+  }
+
+}