diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 5cb7792..c82a4b3 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -1088,7 +1088,7 @@ private function prepareEnvironment() {
 
     // Run all tests as a anonymous user by default, web tests will replace that
     // during the test set up.
-    $this->container->get('current_user')->setAccount(new AnonymousUserSession());
+    $this->container->set('current_user', new AnonymousUserSession());
 
     \Drupal::setContainer($this->container);