diff --git a/_layouts/help.html b/_layouts/help.html
index 80b12fc..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">
@@ -19,7 +23,7 @@
 		  <div class="col-sm-2 hidden-xs">
 				<ul class="nav nav-pills nav-stacked" id="help-nav">
 					{% for h in help_pages %}
-					<li{% if h.mirrorid == page.mirrorid or h.redirect_help_id == page.mirrorid %} class="active"{%endif%}><a href="{{h.url}}">{{h.mirrorid}}</a></li>
+					<li{% if h.mirrorid == page.mirrorid or h.redirect_help_id == page.mirrorid %} class="active"{%endif%} id="toc-{{h.mirrorid}}"><a href="{{h.url}}">{{h.mirrorid}}</a></li>
 					{% endfor %}
 				</ul>
 			</div><!-- sidenave -->
@@ -30,7 +34,7 @@
 							<label>选择帮助条目: </label>
 							<select class="form-control" id="help-select">
 								{% for h in help_pages %}
-								<option data-help-url="{{h.url}}"{% if h.mirrorid == page.mirrorid%} selected{%endif%}>{{h.mirrorid}}</option>
+								<option data-help-url="{{h.url}}"{% if h.mirrorid == page.mirrorid%} selected{%endif%} id="toc-{{h.mirrorid}}">{{h.mirrorid}}</option>
 								{% endfor %}
 							</select>
 						</div>
diff --git a/static/js/help.es6 b/static/js/help.es6
index 1a9e036..957d559 100644
--- a/static/js/help.es6
+++ b/static/js/help.es6
@@ -35,6 +35,18 @@ $(document).ready(() => {
 		let help_url = $(ev.target).find("option:selected").data('help-url');
 		window.location = `${window.location.protocol}//${window.location.host}${help_url}`;
 	});
+
+	$.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();
+	});
 });
 
 // vim: ts=2 sts=2 sw=2 noexpandtab