diff --git a/core/lib/Drupal/Component/Scaffold/composer.json b/core/lib/Drupal/Component/Scaffold/composer.json
index 6f77bf7ad0..0c49a9aaa4 100644
--- a/core/lib/Drupal/Component/Scaffold/composer.json
+++ b/core/lib/Drupal/Component/Scaffold/composer.json
@@ -23,5 +23,8 @@
     },
     "extra": {
         "class": "Drupal\\Component\\Scaffold\\Plugin"
+    },
+    "suggest": {
+        "hirak/prestissimo": "Allow simultaneous downloads of multiple scaffold files."
     }
 }
diff --git a/core/tests/Drupal/Tests/Component/Scaffold/FetcherTest.php b/core/tests/Drupal/Tests/Component/Scaffold/FetcherTest.php
index 48f341a6c1..83148bdb04 100644
--- a/core/tests/Drupal/Tests/Component/Scaffold/FetcherTest.php
+++ b/core/tests/Drupal/Tests/Component/Scaffold/FetcherTest.php
@@ -7,6 +7,7 @@
 use Composer\Util\RemoteFilesystem;
 use Drupal\Component\Scaffold\FileFetcher;
 use PHPUnit\Framework\TestCase;
+
 /**
  * Unit tests for the Scaffold FileFetcher.
  *
@@ -26,22 +27,10 @@ class FetcherTest extends TestCase {
    */
   protected $tmpDir;
 
-  /**
-   * @var string
-   */
-  protected $rootDir;
-
-  /**
-   * @var string
-   */
-  protected $tmpReleaseTag;
-
   /**
    * SetUp test.
    */
   public function setUp() {
-    $this->rootDir = realpath(realpath(__DIR__ . '/Scaffold'));
-
     // Prepare temp directory.
     $this->fs = new Filesystem();
     $this->tmpDir = realpath(sys_get_temp_dir()) . DIRECTORY_SEPARATOR . 'drupal-scaffold';
diff --git a/core/tests/Drupal/Tests/Component/Scaffold/PluginTest.php b/core/tests/Drupal/Tests/Component/Scaffold/PluginTest.php
index 92c4338edd..ad05822ed2 100644
--- a/core/tests/Drupal/Tests/Component/Scaffold/PluginTest.php
+++ b/core/tests/Drupal/Tests/Component/Scaffold/PluginTest.php
@@ -30,7 +30,7 @@ class PluginTest extends TestCase {
   protected $tmpDir;
 
   /**
-   * The root directory of the component within the Drupal codebase.
+   * The full path to the scaffold component within the Drupal codebase.
    *
    * @var string
    */
@@ -47,16 +47,23 @@ class PluginTest extends TestCase {
    * SetUp test.
    */
   public function setUp() {
+    $this->fs = new Filesystem();
     // @todo: Change this to be the component root dir when we start testing
     //        components in isolation.
     //        https://www.drupal.org/project/drupal/issues/2943856
     $this->drupalRootDir = dirname(dirname(dirname(dirname(dirname(dirname(__DIR__))))));
-    // Get the root directory of the Scaffold component.
+    // Get the path to the Scaffold component.
     $this->componentRootDir = $this->drupalRootDir . '/core/lib/Drupal/Component/Scaffold';
 
-    // Prepare temp directory.
-    $this->fs = new Filesystem();
-    $this->tmpDir = realpath(sys_get_temp_dir()) . DIRECTORY_SEPARATOR . 'drupal-scaffold';
+    // Prepare temp directory. If the simpletest directory is present, then we
+    // want our temp dir to be inside it.
+    $this->tmpDir = $this->drupalRootDir . '/sites/simpletest';
+    if (is_dir($this->tmpDir)) {
+      $this->tmpDir .= '/drupal-scaffold';
+    }
+    else {
+      $this->tmpDir = realpath(sys_get_temp_dir()) . DIRECTORY_SEPARATOR . 'drupal-scaffold';
+    }
     $this->ensureDirectoryExistsAndClear($this->tmpDir);
     $this->writeComposerJSON();