diff --git a/core/modules/simpletest/src/WebTestBase.php b/core/modules/simpletest/src/WebTestBase.php
index cde113c..8765d3d 100644
--- a/core/modules/simpletest/src/WebTestBase.php
+++ b/core/modules/simpletest/src/WebTestBase.php
@@ -23,6 +23,7 @@
 use Drupal\Tests\TestFileCreationTrait;
 use Drupal\Tests\XdebugRequestTrait;
 use Zend\Diactoros\Uri;
+use Drupal\Component\Render\FormattableMarkup;
 
 /**
  * Test case for typical Drupal tests.