diff --git a/lib/plugins/tag/post_link.js b/lib/plugins/tag/post_link.js
index 5b2f53d27c..ed03669bdf 100644
--- a/lib/plugins/tag/post_link.js
+++ b/lib/plugins/tag/post_link.js
@@ -27,6 +27,7 @@ module.exports = ctx => {
     if (!post) return error;
 
     let title = args.length ? args.join(' ') : post.title;
+    // Let attribute be the true post title so it appears in tooltip.
     const attrTitle = escapeHTML(post.title);
     if (escape === 'true') title = escapeHTML(title);