diff --git a/.changeset/tough-points-arrive.md b/.changeset/tough-points-arrive.md
new file mode 100644
index 000000000000..59c44cef2251
--- /dev/null
+++ b/.changeset/tough-points-arrive.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+fix: add leading / to isr routes
diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 47d5d648ed1a..e9b4909a5b71 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -274,12 +274,12 @@ const plugin = function (defaults = {}) {
 
 					static_config.routes.push({
 						src: src + '$',
-						dest: `${isr_name}${q}`
+						dest: `/${isr_name}${q}`
 					});
 
 					static_config.routes.push({
 						src: src + '/__data.json$',
-						dest: `${isr_name}/__data.json${q}`
+						dest: `/${isr_name}/__data.json${q}`
 					});
 				} else if (!singular) {
 					static_config.routes.push({ src: src + '(?:/__data.json)?$', dest: `/${name}` });