diff --git a/lib/md2html.js b/lib/md2html.js
index 34f369e9..82282066 100644
--- a/lib/md2html.js
+++ b/lib/md2html.js
@@ -28,7 +28,7 @@ filter.stdio(function ({ t, c }, format, meta) {
     level = 0;
     return content;
   } else if (t === "Link" && c[2][0][0] === ":") {
-    var id = c[2][0].substring(1);
+    const id = c[2][0].substring(1);
     return [
       filter.RawInline("html", `<a id="${id}" href="#${id}">`),
       ...c[1],