diff -u b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
--- b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -176,7 +176,7 @@
   protected $kernel;
 
   /**
-   * Cookies to set on the curl request.
+   * Cookies to set on curl requests.
    *
    * @var array
    */