diff --git a/core/lib/Drupal/Core/PhpStorage/CacheStorage.php b/core/lib/Drupal/Core/PhpStorage/CacheStorage.php
index 3be4e78..725086a 100644
--- a/core/lib/Drupal/Core/PhpStorage/CacheStorage.php
+++ b/core/lib/Drupal/Core/PhpStorage/CacheStorage.php
@@ -38,9 +38,20 @@ class CacheStorage implements PhpStorageInterface {
    */
   protected $bin;
 
+  /**
+   * @var callable
+   */
+  protected $cacheBackendFactory;
+
   public function __construct(array $configuration) {
     $this->secret = $configuration['secret'];
     $this->bin = $configuration['bin'];
+    if (isset($configuration['cache_backend_factory']) && is_callable($configuration['cache_backend_factory'])) {
+      $this->cacheBackendFactory = $configuration['cache_backend_factory'];
+    }
+    else {
+      $this->cacheBackendFactory = [$this, 'getDatabaseBackend'];
+    }
   }
 
   /**
@@ -67,7 +78,7 @@ public function load($name) {
     // multiple times by the classloader as the container class is loaded.
     // So for better performance use the phar protocol.
     stream_wrapper_unregister('phar');
-    stream_wrapper_register('phar', 'Drupal\Core\StreamWrapper\SpecialCacheStream');
+    stream_wrapper_register('phar', 'Drupal\Core\StreamWrapper\SpecialInMemoryStream');
     SpecialInMemoryStream::init($this, $cached->data);
     $return = (include "phar://$name") !== FALSE;
     #var_dump(opcache_get_status(TRUE)['scripts']["phar://$name"]);
@@ -160,19 +171,20 @@ public function listAll() {
    */
   protected function cacheBackend() {
     if (!isset($this->cacheBackend)) {
-      $bootstrap_php_storage = Settings::get('php_storage_cache_backend');
-      if (is_callable($bootstrap_php_storage)) {
-        $this->cacheBackend = $bootstrap_php_storage();
-      }
-      else {
-        $connection = Database::getConnection();
-        $this->cacheBackend = new DatabaseBackend($connection, new DatabaseCacheTagsChecksum($connection), 'php_' . $this->bin);
-      }
+      $this->cacheBackend = call_user_func($this->cacheBackendFactory);
     }
     return $this->cacheBackend;
   }
 
   /**
+   * Construct a database cache backend.
+   */
+  protected function getDatabaseBackend() {
+    $connection = Database::getConnection();
+    return new DatabaseBackend($connection, new DatabaseCacheTagsChecksum($connection), 'php_' . $this->bin);
+  }
+
+  /**
    * Return a secret key based on the filename.
    *
    * By using a secret key, a SQL injection does not lead immediately to
diff --git a/core/tests/Drupal/Tests/Core/PhpStorage/CacheStorageTest.php b/core/tests/Drupal/Tests/Core/PhpStorage/CacheStorageTest.php
index 299952b..c0e47ff 100644
--- a/core/tests/Drupal/Tests/Core/PhpStorage/CacheStorageTest.php
+++ b/core/tests/Drupal/Tests/Core/PhpStorage/CacheStorageTest.php
@@ -29,8 +29,11 @@ class CacheStorageTest extends PhpStorageTestBase {
    */
   public function testCRUD() {
     $secret = $this->randomMachineName();
-    $storage = new CacheStorage(['secret' => $secret, 'bin' => 'test']);
-    new Settings(['php_storage_cache_backend' => function () { return new MemoryBackend('');}]);
+    $storage = new CacheStorage([
+      'secret' => $secret,
+      'cache_backend_factory' => function () { return new MemoryBackend('');},
+      'bin' => 'test'
+    ]);
     $this->assertCRUD($storage);
   }