diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index 72f0b169c902c80e1ba7586fd832427899ca573c..0146607aa6fb3a9a8939edb9766e0368f29751c9 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -131,7 +131,7 @@ abstract class KernelTestBase extends \PHPUnit_Framework_TestCase implements Ser
   /**
    * @var \Drupal\Core\DependencyInjection\ContainerBuilder
    */
-  protected static $initialContainerBuilder;
+  private static $initialContainerBuilder;
 
   /**
    * Modules to enable.
@@ -319,7 +319,7 @@ public function getDatabasePrefix() {
   /**
    * Bootstraps a kernel for a test.
    */
-  protected function bootKernel() {
+  private function bootKernel() {
     $this->setSetting('container_yamls', []);
     // Allow for test-specific overrides.
     $settings_services_file = $this->root . '/sites/default' . '/testing.services.yml';
@@ -501,7 +501,7 @@ protected function getDatabaseConnectionInfo() {
    * @return \Drupal\Core\DependencyInjection\ContainerBuilder
    *   A clone of the precompiled, empty service container.
    */
-  protected function getCompiledContainerBuilder(array $modules) {
+  private function getCompiledContainerBuilder(array $modules) {
     if (!isset(self::$initialContainerBuilder)) {
       $kernel = new DrupalKernel('testing', $this->classLoader, FALSE);
       $kernel->setSitePath($this->siteDirectory);
@@ -567,7 +567,7 @@ protected function initFileCache() {
    * @see \Drupal\Tests\KernelTestBase::enableModules()
    * @see \Drupal\Core\Extension\ModuleHandler::add()
    */
-  protected function getExtensionsForModules(array $modules) {
+  private function getExtensionsForModules(array $modules) {
     $extensions = array();
     $discovery = new ExtensionDiscovery($this->root);
     $discovery->setProfileDirectories(array());
@@ -1031,7 +1031,7 @@ protected function vfsDump() {
    *
    * @return array
    */
-  protected static function getModulesToEnable($class) {
+  private static function getModulesToEnable($class) {
     $modules = array();
     while ($class) {
       if (property_exists($class, 'modules')) {
diff --git a/core/tests/Drupal/Tests/BrowserTestBase.php b/core/tests/Drupal/Tests/BrowserTestBase.php
index 79390697ef12475805e76997de1204bdf059a2b3..ea88906dc5abebda5a3bee160636bda1a592a9cc 100644
--- a/core/tests/Drupal/Tests/BrowserTestBase.php
+++ b/core/tests/Drupal/Tests/BrowserTestBase.php
@@ -1200,7 +1200,7 @@ protected function installParameters() {
    * @see drupal_valid_test_ua()
    * @see BrowserTestBase::prepareEnvironment()
    */
-  protected function prepareDatabasePrefix() {
+  private function prepareDatabasePrefix() {
     // Ensure that the generated test site directory does not exist already,
     // which may happen with a large amount of concurrent threads and
     // long-running tests.
@@ -1216,7 +1216,7 @@ protected function prepareDatabasePrefix() {
    *
    * @see BrowserTestBase::prepareEnvironment()
    */
-  protected function changeDatabasePrefix() {
+  private function changeDatabasePrefix() {
     if (empty($this->databasePrefix)) {
       $this->prepareDatabasePrefix();
     }