diff --git a/.changeset/tidy-actors-relate.md b/.changeset/tidy-actors-relate.md
new file mode 100644
index 000000000..50afa24bb
--- /dev/null
+++ b/.changeset/tidy-actors-relate.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/vercel': patch
+---
+
+Improve file detection of the middleware file handler
diff --git a/packages/integrations/vercel/package.json b/packages/integrations/vercel/package.json
index b7beb4917..0ed2656e8 100644
--- a/packages/integrations/vercel/package.json
+++ b/packages/integrations/vercel/package.json
@@ -47,7 +47,7 @@
     "build": "astro-scripts build \"src/**/*.ts\" && tsc",
     "build:ci": "astro-scripts build \"src/**/*.ts\"",
     "dev": "astro-scripts dev \"src/**/*.ts\"",
-    "test": "mocha --exit --timeout 20000 test/"
+    "test": "mocha --exit --timeout 20000 --file \"./test/setup.js\" test/"
   },
   "dependencies": {
     "@astrojs/internal-helpers": "^0.1.1",
diff --git a/packages/integrations/vercel/src/serverless/middleware.ts b/packages/integrations/vercel/src/serverless/middleware.ts
index c28425f4c..742740f64 100644
--- a/packages/integrations/vercel/src/serverless/middleware.ts
+++ b/packages/integrations/vercel/src/serverless/middleware.ts
@@ -50,7 +50,7 @@ function edgeMiddlewareTemplate(middlewarePath: string, vercelEdgeMiddlewareHand
 	const filePathEdgeMiddleware = fileURLToPath(vercelEdgeMiddlewareHandlerPath);
 	let handlerTemplateImport = '';
 	let handlerTemplateCall = '{}';
-	if (existsSync(filePathEdgeMiddleware) + '.js' || existsSync(filePathEdgeMiddleware) + '.ts') {
+	if (existsSync(filePathEdgeMiddleware + '.js') || existsSync(filePathEdgeMiddleware + '.ts')) {
 		const stringified = JSON.stringify(filePathEdgeMiddleware.replace(/\\/g, '/'));
 		handlerTemplateImport = `import handler from ${stringified}`;
 		handlerTemplateCall = `handler({ request, context })`;
diff --git a/packages/integrations/vercel/test/edge-middleware.test.js b/packages/integrations/vercel/test/edge-middleware.test.js
index dd4b25b67..c713c5464 100644
--- a/packages/integrations/vercel/test/edge-middleware.test.js
+++ b/packages/integrations/vercel/test/edge-middleware.test.js
@@ -1,30 +1,33 @@
 import { loadFixture } from './test-utils.js';
-import { expect, use } from 'chai';
+import { expect } from 'chai';
 import chaiJestSnapshot from 'chai-jest-snapshot';
 
-use(chaiJestSnapshot);
-
-describe('Serverless prerender', () => {
-	/** @type {import('./test-utils').Fixture} */
-	let fixture;
-
-	beforeEach(function () {
-		chaiJestSnapshot.configureUsingMochaContext(this);
-	});
-
-	before(async () => {
-		chaiJestSnapshot.resetSnapshotRegistry();
-		fixture = await loadFixture({
-			root: './fixtures/middleware/',
+describe('Vercel edge middleware', () => {
+	it('with edge handle file, should successfully build the middleware', async () => {
+		const fixture = await loadFixture({
+			root: './fixtures/middleware-with-edge-file/',
 		});
-	});
-
-	it('build successfully the middleware edge file', async () => {
 		await fixture.build();
 		const contents = await fixture.readFile(
 			// this is abysmal...
-			'../.vercel/output/functions/render.func/packages/integrations/vercel/test/fixtures/middleware/dist/middleware.mjs'
+			'../.vercel/output/functions/render.func/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/dist/middleware.mjs'
 		);
-		expect(contents).to.matchSnapshot();
+		expect(contents.includes('title:')).to.be.true;
+		chaiJestSnapshot.setTestName('Middleware with handler file');
+		expect(contents).to.matchSnapshot(true);
+	});
+
+	it('with edge handle file, should successfully build the middleware', async () => {
+		const fixture = await loadFixture({
+			root: './fixtures/middleware-without-edge-file/',
+		});
+		await fixture.build();
+		const contents = await fixture.readFile(
+			// this is abysmal...
+			'../.vercel/output/functions/render.func/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/dist/middleware.mjs'
+		);
+		expect(contents.includes('title:')).to.be.false;
+		chaiJestSnapshot.setTestName('Middleware without handler file');
+		expect(contents).to.matchSnapshot(true);
 	});
 });
diff --git a/packages/integrations/vercel/test/edge-middleware.test.js.snap b/packages/integrations/vercel/test/edge-middleware.test.js.snap
index fe82ccff9..754aebc8f 100644
--- a/packages/integrations/vercel/test/edge-middleware.test.js.snap
+++ b/packages/integrations/vercel/test/edge-middleware.test.js.snap
@@ -1,14 +1,14 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`Serverless prerender build successfully the middleware edge file 1`] = `
-"// test/fixtures/middleware/src/vercel-edge-middleware.js
+exports[`Middleware with handler file 1`] = `
+"// test/fixtures/middleware-with-edge-file/src/vercel-edge-middleware.js
 function vercel_edge_middleware_default({ request, context }) {
   return {
     title: \\"Hello world\\"
   };
 }
 
-// test/fixtures/middleware/dist/middleware2.mjs
+// test/fixtures/middleware-with-edge-file/dist/middleware2.mjs
 var onRequest = async (context, next) => {
   const response = await next();
   return response;
@@ -38,3 +38,35 @@ export {
 };
 "
 `;
+
+exports[`Middleware without handler file 1`] = `
+"// test/fixtures/middleware-without-edge-file/dist/middleware2.mjs
+var onRequest = async (context, next) => {
+  const response = await next();
+  return response;
+};
+
+// <stdin>
+import { createContext, trySerializeLocals } from \\"astro/middleware\\";
+async function middleware(request, context) {
+  const url = new URL(request.url);
+  const ctx = createContext({
+    request,
+    params: {}
+  });
+  ctx.locals = {};
+  const next = async () => {
+    const response = await fetch(url, {
+      headers: {
+        \\"x-astro-locals\\": trySerializeLocals(ctx.locals)
+      }
+    });
+    return response;
+  };
+  return onRequest(ctx, next);
+}
+export {
+  middleware as default
+};
+"
+`;
diff --git a/packages/integrations/vercel/test/fixtures/middleware/astro.config.mjs b/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/astro.config.mjs
similarity index 100%
rename from packages/integrations/vercel/test/fixtures/middleware/astro.config.mjs
rename to packages/integrations/vercel/test/fixtures/middleware-with-edge-file/astro.config.mjs
diff --git a/packages/integrations/vercel/test/fixtures/middleware/package.json b/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/package.json
similarity index 70%
rename from packages/integrations/vercel/test/fixtures/middleware/package.json
rename to packages/integrations/vercel/test/fixtures/middleware-with-edge-file/package.json
index 9ba60852d..2579a8c92 100644
--- a/packages/integrations/vercel/test/fixtures/middleware/package.json
+++ b/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/package.json
@@ -1,5 +1,5 @@
 {
-  "name": "@test/vercel-edge-middleware",
+  "name": "@test/vercel-edge-middleware-with-edge-file",
   "version": "0.0.0",
   "private": true,
   "dependencies": {
diff --git a/packages/integrations/vercel/test/fixtures/middleware/src/middleware.js b/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/src/middleware.js
similarity index 100%
rename from packages/integrations/vercel/test/fixtures/middleware/src/middleware.js
rename to packages/integrations/vercel/test/fixtures/middleware-with-edge-file/src/middleware.js
diff --git a/packages/integrations/vercel/test/fixtures/middleware/src/pages/index.astro b/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/src/pages/index.astro
similarity index 100%
rename from packages/integrations/vercel/test/fixtures/middleware/src/pages/index.astro
rename to packages/integrations/vercel/test/fixtures/middleware-with-edge-file/src/pages/index.astro
diff --git a/packages/integrations/vercel/test/fixtures/middleware/src/vercel-edge-middleware.js b/packages/integrations/vercel/test/fixtures/middleware-with-edge-file/src/vercel-edge-middleware.js
similarity index 100%
rename from packages/integrations/vercel/test/fixtures/middleware/src/vercel-edge-middleware.js
rename to packages/integrations/vercel/test/fixtures/middleware-with-edge-file/src/vercel-edge-middleware.js
diff --git a/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/astro.config.mjs b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/astro.config.mjs
new file mode 100644
index 000000000..321a8bde3
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/astro.config.mjs
@@ -0,0 +1,10 @@
+import {defineConfig} from "astro/config";
+import vercel from "@astrojs/vercel/serverless";
+
+export default defineConfig({
+    adapter: vercel(),
+    build: {
+        excludeMiddleware: true
+    },
+    output: 'server'
+});
\ No newline at end of file
diff --git a/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/package.json b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/package.json
new file mode 100644
index 000000000..d5638ce16
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/package.json
@@ -0,0 +1,9 @@
+{
+  "name": "@test/vercel-edge-middleware-without-edge-file",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "@astrojs/vercel": "workspace:*",
+    "astro": "workspace:*"
+  }
+}
diff --git a/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/src/middleware.js b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/src/middleware.js
new file mode 100644
index 000000000..349a0aa79
--- /dev/null
+++ b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/src/middleware.js
@@ -0,0 +1,8 @@
+/**
+ * @type {import("astro").MiddlewareResponseHandler}
+ */
+export const onRequest = async (context, next) => {
+	const test = 'something';
+	const response = await next();
+	return response;
+};
diff --git a/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/src/pages/index.astro b/packages/integrations/vercel/test/fixtures/middleware-without-edge-file/src/pages/index.astro
new file mode 100644
index 000000000..e69de29bb
diff --git a/packages/integrations/vercel/test/setup.js b/packages/integrations/vercel/test/setup.js
new file mode 100644
index 000000000..c53aa9894
--- /dev/null
+++ b/packages/integrations/vercel/test/setup.js
@@ -0,0 +1,12 @@
+import { use } from 'chai';
+import chaiJestSnapshot from 'chai-jest-snapshot';
+
+use(chaiJestSnapshot);
+
+before(function () {
+	chaiJestSnapshot.resetSnapshotRegistry();
+});
+
+beforeEach(function () {
+	chaiJestSnapshot.configureUsingMochaContext(this);
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 54fa7ad4d..ee1bf68e2 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4944,7 +4944,16 @@ importers:
         specifier: workspace:*
         version: link:../../../../../astro
 
-  packages/integrations/vercel/test/fixtures/middleware:
+  packages/integrations/vercel/test/fixtures/middleware-with-edge-file:
+    dependencies:
+      '@astrojs/vercel':
+        specifier: workspace:*
+        version: link:../../..
+      astro:
+        specifier: workspace:*
+        version: link:../../../../../astro
+
+  packages/integrations/vercel/test/fixtures/middleware-without-edge-file:
     dependencies:
       '@astrojs/vercel':
         specifier: workspace:*