diff --git a/core/lib/Drupal/Core/Extension/ModuleInstaller.php b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
index 0048ebc..7267aec 100644
--- a/core/lib/Drupal/Core/Extension/ModuleInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
@@ -437,7 +437,7 @@ public function uninstall(array $module_list, $uninstall_dependents = TRUE) {
       $schema_store = \Drupal::keyValue('system.schema');
       $schema_store->delete($module);
     }
-    \Drupal::service('router.builder')->rebuild();
+    \Drupal::service('router.builder')->rebuildIfNeeded();
     drupal_get_installed_schema_version(NULL, TRUE);
 
     // Let other modules react.
diff --git a/core/lib/Drupal/Core/Routing/RouteProvider.php b/core/lib/Drupal/Core/Routing/RouteProvider.php
index 86ecbd1..e831815 100644
--- a/core/lib/Drupal/Core/Routing/RouteProvider.php
+++ b/core/lib/Drupal/Core/Routing/RouteProvider.php
@@ -163,6 +163,8 @@ public function getRoutesByNames($names) {
       throw new \InvalidArgumentException('You must specify the route names to load');
     }
 
+    $this->routeBuilder->rebuildIfNeeded();
+
     $routes_to_load = array_diff($names, array_keys($this->routes));
     if ($routes_to_load) {
       $result = $this->connection->query('SELECT name, route FROM {' . $this->connection->escapeTable($this->tableName) . '} WHERE name IN ( :names[] )', array(':names[]' => $routes_to_load));