diff --git a/src/prerender.ts b/src/prerender.ts
index fc4a3ed91a..d2b1a35894 100644
--- a/src/prerender.ts
+++ b/src/prerender.ts
@@ -47,9 +47,10 @@ export async function prerender (nitro: Nitro) {
     if (res.status !== 200) {
       throw new Error(`[${res.status}] ${res.statusText}`)
     }
+
+    const isImplicitHTML = !route.endsWith('.html') && (res.headers.get('content-type') || '').includes('html')
     const routeWithIndex = route.endsWith('/') ? route + 'index' : route
-    const isImplicitHTML = (res.headers.get('content-type') || '').includes('html')
-    const fileName = isImplicitHTML ? routeWithIndex + '.html' : routeWithIndex
+    const fileName = isImplicitHTML ? route + '/index.html' : routeWithIndex
     const filePath = join(nitro.options.output.publicDir, fileName)
     await writeFile(filePath, contents)
     // Crawl Links
diff --git a/test/fixture/api/hello.ts b/test/fixture/api/hello.ts
index 2d81ce2188..22c4854507 100644
--- a/test/fixture/api/hello.ts
+++ b/test/fixture/api/hello.ts
@@ -1 +1 @@
-export default () => 'Hello API'
+export default () => ({ message: 'Hello API' })
diff --git a/test/tests.ts b/test/tests.ts
index 1218f819c6..c48ec47511 100644
--- a/test/tests.ts
+++ b/test/tests.ts
@@ -81,7 +81,7 @@ export function testNitro (ctx: Context, getHandler: () => TestHandler | Promise
 
   it('API Works', async () => {
     const { data: helloData } = await callHandler({ url: '/api/hello' })
-    expect(helloData).to.have.string('Hello API')
+    expect(helloData).to.toMatchObject({ message: 'Hello API' })
 
     const { data: heyData } = await callHandler({ url: '/api/hey' })
     expect(heyData).to.have.string('Hey API')