diff --git a/playground/assets/__tests__/assets.spec.ts b/playground/assets/__tests__/assets.spec.ts
index 70d0fcfe4e8e54..ab482bcdef3d2b 100644
--- a/playground/assets/__tests__/assets.spec.ts
+++ b/playground/assets/__tests__/assets.spec.ts
@@ -8,6 +8,7 @@ import {
   getBg,
   getColor,
   isBuild,
+  isServe,
   listAssets,
   notifyRebuildComplete,
   page,
@@ -60,6 +61,22 @@ test('should fallback to index.html when accessing non-existant html file', asyn
   expect((await fetchPath('doesnt-exist.html')).status).toBe(200)
 })
 
+describe.runIf(isServe)('outside base', () => {
+  test('should get a 404 with html', async () => {
+    const res = await fetch(new URL('/baz', viteTestUrl), {
+      headers: { Accept: 'text/html,*/*' },
+    })
+    expect(res.status).toBe(404)
+    expect(res.headers.get('Content-Type')).toBe('text/html')
+  })
+
+  test('should get a 404 with text', async () => {
+    const res = await fetch(new URL('/baz', viteTestUrl))
+    expect(res.status).toBe(404)
+    expect(res.headers.get('Content-Type')).toBe('text/plain')
+  })
+})
+
 describe('injected scripts', () => {
   test('@vite/client', async () => {
     const hasClient = await page.$(