diff --git a/src/components/EditionToc.astro b/src/components/EditionToc.astro
index 5279142..f10e9b6 100644
--- a/src/components/EditionToc.astro
+++ b/src/components/EditionToc.astro
@@ -11,7 +11,8 @@ const {
 const entries = (await getCollection(collection))
   .sort((a, b) => (a.data.order ?? 0) - (b.data.order ?? 0));
 
-const href = (slug) => `${basePath}/${slug}/`;
+const routeSlug = (entry) => String(entry.id || "").replace(/\.(md|mdx)$/i, "");
+const href = (entry) => `${basePath}/${routeSlug(entry)}/`;
 ---
 
 <nav class="toc-global" aria-label={label}>
@@ -21,10 +22,12 @@ const href = (slug) => `${basePath}/${slug}/`;
 
   <ol class="toc-global__list">
     {entries.map((e) => {
-      const active = e.slug === currentSlug;
+      const entrySlug = routeSlug(e);
+      const active = entrySlug === currentSlug;
+
       return (
         <li class={`toc-item ${active ? "is-active" : ""}`}>
-          <a class="toc-link" href={href(e.slug)} aria-current={active ? "page" : undefined}>
+          <a class="toc-link" href={href(e)} aria-current={active ? "page" : undefined}>
             <span class="toc-link__row">
               {active ? (
                 <span class="toc-active-indicator" aria-hidden="true">👉</span>