diff --git a/_layouts/help.html b/_layouts/help.html
index 2069134..2c2e475 100644
--- a/_layouts/help.html
+++ b/_layouts/help.html
@@ -12,6 +12,10 @@
 </script>
 {% endif %}
 
+<script>
+	window.mirrorId = "{{page.mirrorid}}";
+</script>
+
 {% assign help_pages = site.categories["help"] | sort: 'mirrorid' %}
 <div id="help-page">
 	<div class="container">
diff --git a/static/js/help.es6 b/static/js/help.es6
index 69f2834..957d559 100644
--- a/static/js/help.es6
+++ b/static/js/help.es6
@@ -39,6 +39,11 @@ $(document).ready(() => {
 	$.getJSON("/static/tunasync.json", (statusData) => {
 		// remove help items for disabled/removed mirrors
 		let availableMirrorIds = new Set(statusData.map(x => x.name));
+		console.log(window.mirrorId);
+		if (!availableMirrorIds.has(window.mirrorId)) {
+			location.href = "/404.html"; // this will break 404 issue submission
+		}
+
 		$('li').filter((_, node) => node.id && node.id.startsWith("toc-") && !availableMirrorIds.has(node.id.slice(4))).remove();
 		$('option').filter((_, node) => node.id && node.id.startsWith("toc-") && !availableMirrorIds.has(node.id.slice(4))).remove();
 	});