diff -u b/core/modules/simpletest/src/BrowserTestBase.php b/core/modules/simpletest/src/BrowserTestBase.php
--- b/core/modules/simpletest/src/BrowserTestBase.php
+++ b/core/modules/simpletest/src/BrowserTestBase.php
@@ -210,7 +210,7 @@
   /**
    * {@inheritdoc}
    */
-  public function setUp() {
+  protected function setUp() {
     global $base_url;
     parent::setUp();
 
@@ -321,7 +321,7 @@
   /**
    * {@inheritdoc}
    */
-  public function tearDown() {
+  protected function tearDown() {
     parent::tearDown();
 
     // Destroy the testing kernel.