diff --git a/docs/404.html b/docs/404.html
index c65a56f2bc..dae070593a 100644
--- a/docs/404.html
+++ b/docs/404.html
@@ -61,7 +61,11 @@
     if (redirectToUrl) {
       fetch(redirectToUrl, {
         method: 'HEAD'
-      }).then(() => {
+      }).then((response) => {
+        if (!response.ok) {
+          is404();
+          return;
+        }
         try {
           window.location.replace(redirectToUrl);
         } catch (err) {
@@ -129,7 +133,7 @@
 </script>
 
 <div class="text-center">
-  <img
+  <img alt="Not Found"
   height="128"
   src="/images/not_found.svg"
   width="128"