diff --git a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
index fe1dca1..532ae19 100644
--- a/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
+++ b/core/modules/block/lib/Drupal/block/Tests/BlockTest.php
@@ -178,7 +178,7 @@ function testHideBlockTitle() {
     $title = $this->randomName(8);
     $machine_name = strtolower($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(
       'machine_name' => $machine_name,
       '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 8316c8b..92c23cd 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 @@ function testSystemMenuRename() {
     $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']);
   }