diff --git a/src/Toc.php b/src/Toc.php
index 98100666c4477880d46691bbed640c83f81f90a4..126867c1c6c885f01eff456d882411cd585303ce 100644
--- a/src/Toc.php
+++ b/src/Toc.php
@@ -340,7 +340,7 @@ class Toc implements TocInterface {
           '#markup' => $header_html,
           '#allowed_tags' => $this->getAllowedTags(),
         ],
-        'url' => Url::fromRoute('<none>', NULL, [
+        'url' => Url::fromRoute('<none>', [], [
             'fragment' => $header_id,
           ]
         ),