diff --git a/core/lib/Drupal/Core/Extension/ExtensionList.php b/core/lib/Drupal/Core/Extension/ExtensionList.php
index 01eca39..ebc2425 100644
--- a/core/lib/Drupal/Core/Extension/ExtensionList.php
+++ b/core/lib/Drupal/Core/Extension/ExtensionList.php
@@ -150,6 +150,20 @@ protected function getCacheId() {
   }
 
   /**
+   * Determines if an extension exists in the filesystem.
+   *
+   * @param string $name
+   *   The machine name of the extension.
+   *
+   * @return bool
+   *   true if the extension exists (whether installed or not) and false if not.
+   */
+  public function extensionExists($name) {
+    $extensions = $this->listExtensions();
+    return isset($extensions[$name]);
+  }
+
+  /**
    * Returns the human readable name of the extension.
    *
    * @param string $machine_name
diff --git a/core/lib/Drupal/Core/Updater/Module.php b/core/lib/Drupal/Core/Updater/Module.php
index a7a1863..f3480df 100644
--- a/core/lib/Drupal/Core/Updater/Module.php
+++ b/core/lib/Drupal/Core/Updater/Module.php
@@ -54,8 +54,7 @@ public static function getRootDirectoryRelativePath() {
   public function isInstalled() {
     // Check if the module exists in the file system, regardless of whether it
     // is enabled or not.
-    $modules = \Drupal::state()->get('system.module.files', array());
-    return isset($modules[$this->name]);
+    return \Drupal::service('module_listing')->extensionExists($this->name);
   }
 
   /**
diff --git a/core/modules/simpletest/src/KernelTestBase.php b/core/modules/simpletest/src/KernelTestBase.php
index 10463d9..87cf4f6 100644
--- a/core/modules/simpletest/src/KernelTestBase.php
+++ b/core/modules/simpletest/src/KernelTestBase.php
@@ -105,7 +105,7 @@ function __construct($test_id = NULL) {
   protected function beforePrepareEnvironment() {
     // Copy/prime extension file lists once to avoid filesystem scans.
     if (!isset($this->moduleFiles)) {
-      $this->moduleFiles = \Drupal::state()->get('system.module.files') ?: array();
+      $this->moduleFiles = \Drupal::cache('default')->get('system.module.files') ?: array();
       $this->themeFiles = \Drupal::state()->get('system.theme.files') ?: array();
     }
   }
@@ -227,7 +227,7 @@ protected function setUp() {
     // Re-inject extension file listings into state, unless the key/value
     // service was overridden (in which case its storage does not exist yet).
     if ($this->container->get('keyvalue') instanceof KeyValueMemoryFactory) {
-      $this->container->get('state')->set('system.module.files', $this->moduleFiles);
+      $this->container->get('cache.default')->set('system.module.files', $this->moduleFiles);
       $this->container->get('state')->set('system.theme.files', $this->themeFiles);
     }
 
diff --git a/core/modules/system/src/Tests/Update/DbDumpTest.php b/core/modules/system/src/Tests/Update/DbDumpTest.php
index 7cd099b..cf31d42 100644
--- a/core/modules/system/src/Tests/Update/DbDumpTest.php
+++ b/core/modules/system/src/Tests/Update/DbDumpTest.php
@@ -125,6 +125,7 @@ protected function setUp() {
       'cachetags',
       'config',
       'cache_bootstrap',
+      'cache_default',
       'cache_discovery',
       'cache_entity',
       'file_managed',
diff --git a/core/tests/Drupal/Tests/Core/Extension/ExtensionListTest.php b/core/tests/Drupal/Tests/Core/Extension/ExtensionListTest.php
index f9a9b16..e644aa1 100644
--- a/core/tests/Drupal/Tests/Core/Extension/ExtensionListTest.php
+++ b/core/tests/Drupal/Tests/Core/Extension/ExtensionListTest.php
@@ -20,6 +20,7 @@
 
 /**
  * @coversDefaultClass \Drupal\Core\Extension\ExtensionList
+ * @group Extension
  */
 class ExtensionListTest extends UnitTestCase {