diff --git a/core/modules/system/src/Tests/Common/AttachedAssetsTest.php b/core/modules/system/src/Tests/Common/AttachedAssetsTest.php
index 97e3042..8098fdd 100644
--- a/core/modules/system/src/Tests/Common/AttachedAssetsTest.php
+++ b/core/modules/system/src/Tests/Common/AttachedAssetsTest.php
@@ -45,7 +45,7 @@ class AttachedAssetsTest extends KernelTestBase {
   /**
    * {@inheritdoc}
    */
-  public static $modules = array('language', 'simpletest', 'common_test', 'system', 'attached_assets_test');
+  public static $modules = array('language', 'simpletest', 'common_test', 'system');
 
   /**
    * {@inheritdoc}
@@ -392,6 +392,9 @@ function testRenderDifferentWeight() {
    * @see attached_assets_test_js_alter()
    */
   function testAlter() {
+    // Enable a test module that alters JS.
+    $this->enableModules(['attached_assets_test']);
+
     // Add jQuery.
     $build['#attached']['library'][] = 'core/jquery';
     $assets = AttachedAssets::createFromRenderArray($build);