diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
index 27bf1b28d30..e06d3b24ee7 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
@@ -177,7 +177,7 @@ class BlockTest extends BlockTestBase {
     $title = $this->randomName(8);
     $id = strtolower($this->randomName(8));
     // Enable a standard block.
-    $default_theme = \Drupal::config('system.theme')->get('default') ?: 'stark';
+    $default_theme = \Drupal::config('system.theme')->get('default');
     $edit = array(
       'id' => $id,
       'region' => 'sidebar_first',
diff --git a/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php b/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php
index 8316c8b72a5..92c23cd625f 100644
--- a/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php
+++ b/core/modules/menu/lib/Drupal/menu/Tests/MenuTest.php
@@ -394,7 +394,7 @@ class MenuTest extends MenuWebTestBase {
     $this->drupalPostForm('admin/structure/menu/manage/main', $edit, t('Save'));
 
     // Make sure menu shows up with new name in block addition.
-    $default_theme = \Drupal::config('system.theme')->get('default') ?: 'stark';
+    $default_theme = \Drupal::config('system.theme')->get('default');
     $this->drupalget('admin/structure/block/list/' . $default_theme);
     $this->assertText($edit['label']);
   }
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 80b02f87bcb..cdfddea4e5a 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -222,7 +222,7 @@ function system_permission() {
     ),
     'view the administration theme' => array(
       'title' => t('View the administration theme'),
-      'description' => \Drupal::config('system.theme')->get('admin') ?: t('This is only used when the site is configured to use a separate administration theme on the <a href="@appearance-url">Appearance</a> page.', array('@appearance-url' => url('admin/appearance'))),
+      'description' => t('This is only used when the site is configured to use a separate administration theme on the <a href="@appearance-url">Appearance</a> page.', array('@appearance-url' => url('admin/appearance'))),
     ),
     'access site reports' => array(
       'title' => t('View site reports'),