diff -u b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
--- b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/Tests/SimpleTestTest.php
@@ -46,7 +46,7 @@
       $this->drupalLogin($admin_user);
     }
     else {
-      $this::$modules = array('non_existent_module');
+      self::$modules = array('non_existent_module');
       parent::setUp();
     }
   }