diff --git a/core/core.services.yml b/core/core.services.yml
index 98b418f..f58e360 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1133,7 +1133,7 @@ services:
     alias: session_handler.storage
   session_handler.storage:
     class: Drupal\Core\Session\SessionHandler
-    arguments: ['@request_stack', '@database']
+    arguments: ['@request_stack', '@database', '%session_write_interval%']
     tags:
       - { name: backend_overridable }
   session_handler.write_check:
diff --git a/core/lib/Drupal/Core/Session/SessionHandler.php b/core/lib/Drupal/Core/Session/SessionHandler.php
index 42daba5..0001af8 100644
--- a/core/lib/Drupal/Core/Session/SessionHandler.php
+++ b/core/lib/Drupal/Core/Session/SessionHandler.php
@@ -41,16 +41,26 @@ class SessionHandler extends AbstractProxy implements \SessionHandlerInterface {
   protected $obsoleteSessionIds = array();
 
   /**
+   * The session write interval.
+   *
+   * @var int
+   */
+  protected $sessionWriteInterval;
+
+  /**
    * Constructs a new SessionHandler instance.
    *
    * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
    *   The request stack.
    * @param \Drupal\Core\Database\Connection $connection
    *   The database connection.
+   * @param int $session_write_interval
+   *   The session write interval.
    */
-  public function __construct(RequestStack $request_stack, Connection $connection) {
+  public function __construct(RequestStack $request_stack, Connection $connection, $session_write_interval = 180) {
     $this->requestStack = $request_stack;
     $this->connection = $connection;
+    $this->sessionWriteInterval = $session_write_interval;
   }
 
   /**
@@ -126,7 +136,7 @@ public function write($sid, $value) {
         ->execute();
 
       // Likewise, do not update access time more than once per 180 seconds.
-      if ($user->isAuthenticated() && REQUEST_TIME - $user->getLastAccessedTime() > Settings::get('session_write_interval', 180)) {
+      if ($user->isAuthenticated() && REQUEST_TIME - $user->getLastAccessedTime() > $this->sessionWriteInterval) {
         /** @var \Drupal\user\UserStorageInterface $storage */
         $storage = \Drupal::entityManager()->getStorage('user');
         $storage->updateLastAccessTimestamp($user, REQUEST_TIME);
diff --git a/core/modules/system/src/Tests/File/DirectoryTest.php b/core/modules/system/src/Tests/File/DirectoryTest.php
index 0822063..5594b7c 100644
--- a/core/modules/system/src/Tests/File/DirectoryTest.php
+++ b/core/modules/system/src/Tests/File/DirectoryTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\system\Tests\File;
 
 use Drupal\Component\PhpStorage\FileStorage;
+use Drupal\Core\File\FileSystem;
 
 /**
  * Tests operations dealing with directories.
@@ -81,7 +82,8 @@ function testFileCheckDirectoryHandling() {
       $this->assertFalse(file_prepare_directory($directory, 0), 'Error reported for a non-writeable directory.', 'File');
 
       // Test directory permission modification.
-      $this->settingsSet('file_chmod_directory', 0777);
+      $this->container->set('file_system', new FileSystem($this->container->get('stream_wrapper_manager'), ['directory' => 0777], $this->container->get('logger.channel.file')));
+
       $this->assertTrue(file_prepare_directory($directory, FILE_MODIFY_PERMISSIONS), 'No error reported when making directory writeable.', 'File');
     }
 
diff --git a/core/modules/system/src/Tests/File/UnmanagedSaveDataTest.php b/core/modules/system/src/Tests/File/UnmanagedSaveDataTest.php
index fc715c6..2e1e507 100644
--- a/core/modules/system/src/Tests/File/UnmanagedSaveDataTest.php
+++ b/core/modules/system/src/Tests/File/UnmanagedSaveDataTest.php
@@ -6,6 +6,7 @@
  */
 
 namespace Drupal\system\Tests\File;
+use Drupal\Core\File\FileSystem;
 
 /**
  * Tests the file_unmanaged_save_data() function.
@@ -18,7 +19,8 @@ class UnmanagedSaveDataTest extends FileTestBase {
    */
   function testFileSaveData() {
     $contents = $this->randomMachineName(8);
-    $this->settingsSet('file_chmod_file', 0777);
+    $this->container->set('file_system', new FileSystem($this->container->get('stream_wrapper_manager'), ['file' => 0777], $this->container->get('logger.channel.file')));
+
 
     // No filename.
     $filepath = file_unmanaged_save_data($contents);
diff --git a/core/modules/system/src/Tests/Session/SessionTest.php b/core/modules/system/src/Tests/Session/SessionTest.php
index 0921f66..c4f89c5 100644
--- a/core/modules/system/src/Tests/Session/SessionTest.php
+++ b/core/modules/system/src/Tests/Session/SessionTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Session;
 
+use Drupal\Component\Serialization\Yaml;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -228,13 +229,12 @@ function testSessionWrite() {
     $this->assertEqual($times4->timestamp, $times3->timestamp, 'Sessions table was not updated.');
 
     // Force updating of users and sessions table once per second.
-    $this->settingsSet('session_write_interval', 0);
-    // Write that value also into the test settings.php file.
-    $settings['settings']['session_write_interval'] = (object) array(
-      'value' => 0,
-      'required' => TRUE,
-    );
-    $this->writeSettings($settings);
+    $filename = $this->siteDirectory . '/services.yml';
+    $data = Yaml::decode(file_get_contents($filename));
+    $data['parameters']['session_write_interval'] = 0;
+    file_put_contents($filename, Yaml::encode($data));
+    $this->rebuildContainer();
+
     $this->drupalGet('');
     $times5 = db_query($sql, array(':uid' => $user->id()))->fetchObject();
     $this->assertNotEqual($times5->access, $times4->access, 'Users table was updated.');