diff --git a/core/lib/Drupal/Core/Test/TestRunnerKernel.php b/core/lib/Drupal/Core/Test/TestRunnerKernel.php
index 85d84b75a7bd0f2ee72a94e5bd979bdf906c37a1..2315693eacf442ce5d7c5d44a8f13a73a688d7d3 100644
--- a/core/lib/Drupal/Core/Test/TestRunnerKernel.php
+++ b/core/lib/Drupal/Core/Test/TestRunnerKernel.php
@@ -87,8 +87,8 @@ public function boot() {
 
     // Create the build/artifacts directory if necessary.
     include_once $this->getAppRoot() . '/core/includes/file.inc';
-    if (!is_dir('public://simpletest')) {
-      mkdir('public://simpletest', 0777, TRUE);
+    if (!is_dir('public://simpletest') && !@mkdir('public://simpletest', 0777, TRUE) && !is_dir('public://simpletest')) {
+      throw new \RuntimeException('Unable to create directory: public://simpletest');
     }
   }