diff --git a/core/modules/simpletest/src/Tests/SimpleTestTest.php b/core/modules/simpletest/src/Tests/SimpleTestTest.php
index 8d08883..3166123 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestTest.php
@@ -8,7 +8,9 @@
 namespace Drupal\simpletest\Tests;
 
 use Drupal\Component\Utility\Crypt;
+use Drupal\Core\Url;
 use Drupal\simpletest\WebTestBase;
+use Drupal\user\Entity\User;
 
 /**
  * Tests SimpleTest's web interface: check that the intended tests were run and
@@ -265,9 +267,8 @@ function confirmStubTestResults() {
 
     // Check that we have two exceeded memory errors. One for the frontpage and
     // one for the user page which the request is redirected to.
-    $base_url = rtrim(\Drupal::request()->getSchemeAndHttpHost() . '/' . \Drupal::request()->getBaseUrl(), '/');
-    $this->assertAssertion("exceeded acceptable maximum (1M) on url $base_url/", 'Other', 'Fail', 'WebTestBase.php', 'Drupal\simpletest\WebTestBase->curlExec()');
-    $this->assertAssertion("exceeded acceptable maximum (1M) on url $base_url/user/2", 'Other', 'Fail', 'WebTestBase.php', 'Drupal\simpletest\WebTestBase->curlExec()');
+    $this->assertAssertion('exceeded acceptable maximum (1M) on url ' . Url::fromRoute('<front>')->setAbsolute()->toString(), 'Other', 'Fail', 'WebTestBase.php', 'Drupal\simpletest\WebTestBase->curlExec()');
+    $this->assertAssertion('exceeded acceptable maximum (1M) on url ' . User::load(2)->urlInfo()->setAbsolute()->toString(), 'Other', 'Fail', 'WebTestBase.php', 'Drupal\simpletest\WebTestBase->curlExec()');
 
     $this->assertEqual('17 passes, 5 fails, 2 exceptions, 4 debug messages', $this->childTestResults['summary']);