diff --git a/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
index bdd05c7..d9d51fe 100644
--- a/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
@@ -102,7 +102,7 @@ public function onKernelRequestMaintenance(GetResponseEvent $event) {
         // Deliver the 503 page if the site is in maintenance mode and the
         // logged in user is not allowed to bypass it.
         drupal_maintenance_theme();
-        $content = Xss::filterAdmin(String::format($this->config->get('system.maintenance')->get('message'), array(
+        $content = Xss::filterAdmin(String::format($this->config->getEditable('system.maintenance')->get('message'), array(
           '@site' => $this->config->get('system.site')->get('name'),
         )));
         $output = $this->bareHtmlPageRenderer->renderBarePage(['#markup' => $content], $this->t('Site under maintenance'), 'maintenance_page');
diff --git a/core/modules/system/src/Tests/System/SiteMaintenanceTest.php b/core/modules/system/src/Tests/System/SiteMaintenanceTest.php
index 48c592d..046bd2f 100644
--- a/core/modules/system/src/Tests/System/SiteMaintenanceTest.php
+++ b/core/modules/system/src/Tests/System/SiteMaintenanceTest.php
@@ -21,7 +21,7 @@ class SiteMaintenanceTest extends WebTestBase {
    *
    * @var array
    */
-  public static $modules = array('node');
+  public static $modules = array('node', 'locale');
 
   protected $admin_user;
 
@@ -34,7 +34,7 @@ protected function setUp() {
     // Create a user allowed to access site in maintenance mode.
     $this->user = $this->drupalCreateUser(array('access site in maintenance mode'));
     // Create an administrative user.
-    $this->admin_user = $this->drupalCreateUser(array('administer site configuration', 'access site in maintenance mode'));
+    $this->admin_user = $this->drupalCreateUser(array('administer site configuration', 'access site in maintenance mode', 'translate interface', 'administer languages'));
     $this->drupalLogin($this->admin_user);
   }
 
@@ -50,6 +50,7 @@ function testSiteMaintenance() {
 
     $admin_message = t('Operating in maintenance mode. <a href="@url">Go online.</a>', array('@url' => \Drupal::url('system.site_maintenance_mode')));
     $user_message = t('Operating in maintenance mode.');
+    $custom_user_message = t('Deze site is in onderhoud.');
     $offline_message = t('@site is currently under maintenance. We should be back shortly. Thank you for your patience.', array('@site' => $this->config('system.site')->get('name')));
 
     $this->drupalGet('');
@@ -112,5 +113,32 @@ function testSiteMaintenance() {
     // Log in with temporary login link.
     $this->drupalPostForm($path, array(), t('Log in'));
     $this->assertText($user_message);
+
+    $this->drupalLogout();
+    $this->drupalLogin($this->admin_user);
+
+    $langcode = 'es';
+
+    // Add Spanish.
+    $edit = array();
+    $edit['predefined_langcode'] = $langcode;
+    $this->drupalPostForm('admin/config/regional/language/add', $edit, t('Add language'));
+
+    // Make Dutch the default language.
+    $edit = array();
+    $edit['site_default_language'] = 'nl';
+    $this->drupalPostForm(NULL, $edit, t('Save configuration'));
+
+    // Set a custom Dutch maintenance message.
+    $edit = array(
+      'maintenance_mode' => 1,
+      'maintenance_mode_message' => $custom_user_message,
+    );
+    $this->drupalPostForm('admin/config/development/maintenance', $edit, t('Save configuration'));
+
+    // Logout and verify that custom site offline message is displayed.
+    $this->drupalLogout();
+    $this->drupalGet('');
+    $this->assertRaw($offline_message, 'Found the site offline message.');
   }
 }