diff --git a/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php b/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
index 14ec4d3e35e39c9260fc00afd6a850b1ecd1e6a2..5e0795239a81d652cb326001e794ebbf1fea910d 100644
--- a/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
+++ b/core/lib/Drupal/Core/Test/FunctionalTestSetupTrait.php
@@ -78,7 +78,7 @@ protected function prepareSettings() {
     // installation.
     // Not using File API; a potential error must trigger a PHP warning.
     $directory = DRUPAL_ROOT . '/' . $this->siteDirectory;
-    copy(DRUPAL_ROOT . '/sites/default/default.settings.php', $directory . '/settings.php');
+    copy(DRUPAL_ROOT . '/core/assets/scaffold/files/default.settings.php', $directory . '/settings.php');
 
     // The public file system path is created during installation. Additionally,
     // during tests:
@@ -136,7 +136,7 @@ protected function prepareSettings() {
     $settings_services_file = DRUPAL_ROOT . '/' . $this->originalSite . '/testing.services.yml';
     if (!file_exists($settings_services_file)) {
       // Otherwise, use the default services as a starting point for overrides.
-      $settings_services_file = DRUPAL_ROOT . '/sites/default/default.services.yml';
+      $settings_services_file = DRUPAL_ROOT . '/core/assets/scaffold/files/default.services.yml';
     }
 
     // Put the testing-specific service overrides in place.