diff --git a/src/render.ts b/src/render.ts
index fd5cd1f19..093ec6d40 100644
--- a/src/render.ts
+++ b/src/render.ts
@@ -149,7 +149,7 @@ ${parseResult.html}</main>
 function renderListItem(p: Page, path: string): string {
   return `<li class="observablehq-link${
     p.path === path ? " observablehq-link-active" : ""
-  }"><a href="${escapeDoubleQuoted(relativeUrl(path, p.path.replace(/\/index$/, "") || "/"))}">${escapeData(
+  }"><a href="${escapeDoubleQuoted(relativeUrl(path, p.path.replace(/\/index$/, "/") || "/"))}">${escapeData(
     p.name
   )}</a></li>`;
 }
diff --git a/test/output/build/multi/index.html b/test/output/build/multi/index.html
index 5aed50972..dc9dbf850 100644
--- a/test/output/build/multi/index.html
+++ b/test/output/build/multi/index.html
@@ -28,7 +28,7 @@
 <input id="observablehq-sidebar-toggle" type="checkbox">
 <nav id="observablehq-sidebar">
   <ol>
-    <li class="observablehq-link"><a href="./subsection">Sub-Section</a></li>
+    <li class="observablehq-link"><a href="./subsection/">Sub-Section</a></li>
     <li class="observablehq-link observablehq-link-active"><a href="./">Multi test</a></li>
   </ol>
 </nav>
diff --git a/test/output/build/multi/subsection/index.html b/test/output/build/multi/subsection/index.html
index a2ccaa942..3b7956e51 100644
--- a/test/output/build/multi/subsection/index.html
+++ b/test/output/build/multi/subsection/index.html
@@ -15,7 +15,7 @@
 <input id="observablehq-sidebar-toggle" type="checkbox">
 <nav id="observablehq-sidebar">
   <ol>
-    <li class="observablehq-link observablehq-link-active"><a href="../subsection">Sub-Section</a></li>
+    <li class="observablehq-link observablehq-link-active"><a href="./">Sub-Section</a></li>
     <li class="observablehq-link"><a href="../">Multi test</a></li>
   </ol>
 </nav>