diff --git a/core/lib/Drupal/Core/Routing/RouteProvider.php b/core/lib/Drupal/Core/Routing/RouteProvider.php
index 06c3ea7..da9dc1b 100644
--- a/core/lib/Drupal/Core/Routing/RouteProvider.php
+++ b/core/lib/Drupal/Core/Routing/RouteProvider.php
@@ -333,7 +333,7 @@ public function getRoutesPaged($offset, $length = NULL) {
     $select = $this->connection->select($this->tableName, 'router')
       ->fields('router', ['name', 'route']);
 
-    if ($length) {
+    if (isset($length)) {
       $select->range($offset, $length);
     }
 
diff --git a/core/modules/system/src/Tests/Routing/RouteProviderTest.php b/core/modules/system/src/Tests/Routing/RouteProviderTest.php
index 6b6e1d7..be8862c 100644
--- a/core/modules/system/src/Tests/Routing/RouteProviderTest.php
+++ b/core/modules/system/src/Tests/Routing/RouteProviderTest.php
@@ -479,6 +479,10 @@ public function testGetRoutesPaged() {
     $routes = $provider->getRoutesPaged(0);
     $this->assertEqual(array_keys($routes), array_keys($fixture_routes));
 
+    // Query non routes.
+    $routes = $provider->getRoutesPaged(0, 0);
+    $this->assertEqual(array_keys($routes), []);
+
     // Query a limited sets of routes.
     $routes = $provider->getRoutesPaged(1, 2);
     $this->assertEqual(array_keys($routes), array_slice(array_keys($fixture_routes), 1, 2));