diff --git a/core/modules/menu_link_content/src/Tests/Migrate/d6/MigrateMenuLinkTest.php b/core/modules/menu_link_content/src/Tests/Migrate/d6/MigrateMenuLinkTest.php
index f6346fc..795f5f0 100644
--- a/core/modules/menu_link_content/src/Tests/Migrate/d6/MigrateMenuLinkTest.php
+++ b/core/modules/menu_link_content/src/Tests/Migrate/d6/MigrateMenuLinkTest.php
@@ -27,7 +27,6 @@ class MigrateMenuLinkTest extends MigrateDrupal6TestBase {
    */
   protected function setUp() {
     parent::setUp();
-    $this->installSchema('system', ['router']);
     $this->installEntitySchema('menu_link_content');
     $this->executeMigrations(['menu', 'd6_menu_links']);
   }
diff --git a/core/modules/menu_link_content/src/Tests/Migrate/d7/MigrateMenuLinkTest.php b/core/modules/menu_link_content/src/Tests/Migrate/d7/MigrateMenuLinkTest.php
index 6b9814a..cd18579 100644
--- a/core/modules/menu_link_content/src/Tests/Migrate/d7/MigrateMenuLinkTest.php
+++ b/core/modules/menu_link_content/src/Tests/Migrate/d7/MigrateMenuLinkTest.php
@@ -29,7 +29,6 @@ class MigrateMenuLinkTest extends MigrateDrupal7TestBase {
    */
   protected function setUp() {
     parent::setUp();
-    $this->installSchema('system', ['router']);
     $this->installEntitySchema('menu_link_content');
     $this->executeMigration('menu');
   }
diff --git a/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetTest.php b/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetTest.php
index a1fb995..4d43d3a 100644
--- a/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetTest.php
+++ b/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetTest.php
@@ -35,7 +35,6 @@ class MigrateShortcutSetTest extends MigrateDrupal7TestBase {
    */
   protected function setUp() {
     parent::setUp();
-    $this->installSchema('system', array('router'));
     $this->installEntitySchema('shortcut');
     $this->installEntitySchema('menu_link_content');
     $this->executeMigration('d7_shortcut_set');
diff --git a/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetUsersTest.php b/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetUsersTest.php
index c6d4530..18318ed 100644
--- a/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetUsersTest.php
+++ b/core/modules/shortcut/src/Tests/Migrate/d7/MigrateShortcutSetUsersTest.php
@@ -34,7 +34,6 @@ class MigrateShortcutSetUsersTest extends MigrateDrupal7TestBase {
    */
   protected function setUp() {
     parent::setUp();
-    $this->installSchema('system', array('router'));
     $this->installEntitySchema('shortcut');
     $this->installEntitySchema('menu_link_content');
     $this->installSchema('shortcut', ['shortcut_set_users']);
diff --git a/core/modules/simpletest/src/RouteBuilder.php b/core/modules/simpletest/src/RouteBuilder.php
index dea8cde..79441b4 100644
--- a/core/modules/simpletest/src/RouteBuilder.php
+++ b/core/modules/simpletest/src/RouteBuilder.php
@@ -21,18 +21,30 @@ class RouteBuilder implements RouteBuilderInterface, DestructableInterface {
   use DependencySerializationTrait;
 
   /**
+   * @var bool
+   */
+  protected $tableInstalled;
+
+  /**
    * Loads the router builder and installs the router table.
    *
-   * @return object
-   *   Returns the constructed real service.
+   * @param bool $table_needed
+   *   TRUE when the table needs to be installed.
+   *
+   * @return \Drupal\Core\Routing\RouteBuilderInterface|\Drupal\Core\DestructableInterface
+   *   Returns the real route builder.
    */
-  protected function lazyLoadItself() {
+  protected function lazyLoadItself($table_needed = FALSE) {
     if (!isset($this->service)) {
       $container = \Drupal::getContainer();
       $this->service = $container->get('simpletest.router.builder');
+    }
+    if ($table_needed && !$this->tableInstalled) {
       $schema = $container->get('database')->schema();
       if (!$schema->tableExists('router')) {
-        $schema->createTable('router', drupal_get_module_schema('system', 'router'));
+        include_once $container->get('app.root') . '/core/modules/system/system.install';
+        $schema->createTable('router', system_schema()['router']);
+        $this->tableInstalled = TRUE;
       }
     }
     return $this->service;
@@ -49,7 +61,7 @@ public function setRebuildNeeded() {
    * {@inheritdoc}
    */
   public function rebuild() {
-    return $this->lazyLoadItself()->rebuild();
+    return $this->lazyLoadItself(TRUE)->rebuild();
   }
 
   /**
diff --git a/core/modules/system/src/Tests/File/StreamWrapperTest.php b/core/modules/system/src/Tests/File/StreamWrapperTest.php
index 343cd83..5816861 100644
--- a/core/modules/system/src/Tests/File/StreamWrapperTest.php
+++ b/core/modules/system/src/Tests/File/StreamWrapperTest.php
@@ -102,7 +102,6 @@ function testUriFunctions() {
     // Test file_create_url()
     // TemporaryStream::getExternalUrl() uses Url::fromRoute(), which needs
     // route information to work.
-    $this->installSchema('system', 'router');
     $this->container->get('router.builder')->rebuild();
     $this->assertTrue(strpos(file_create_url('temporary://test.txt'), 'system/temporary?file=test.txt'), 'Temporary external URL correctly built.');
     $this->assertTrue(strpos(file_create_url('public://test.txt'), Settings::get('file_public_path') . '/test.txt'), 'Public external URL correctly built.');
diff --git a/core/modules/system/src/Tests/System/TokenReplaceUnitTestBase.php b/core/modules/system/src/Tests/System/TokenReplaceUnitTestBase.php
index 84b5041..a8cd490 100644
--- a/core/modules/system/src/Tests/System/TokenReplaceUnitTestBase.php
+++ b/core/modules/system/src/Tests/System/TokenReplaceUnitTestBase.php
@@ -39,7 +39,6 @@ protected function setUp() {
     parent::setUp();
     // Install default system configuration.
     $this->installConfig(array('system'));
-    $this->installSchema('system', array('router'));
     $this->interfaceLanguage = \Drupal::languageManager()->getCurrentLanguage();
     $this->tokenService = \Drupal::token();
   }