diff --git a/packages/runner/src/types/tasks.ts b/packages/runner/src/types/tasks.ts
index 5cf376b69a06..5c89f1a9cffd 100644
--- a/packages/runner/src/types/tasks.ts
+++ b/packages/runner/src/types/tasks.ts
@@ -411,11 +411,11 @@ interface ExtendedAPI<ExtraContext> {
   runIf: (condition: any) => ChainableTestAPI<ExtraContext>
 }
 
-export type CustomAPI<ExtraContext = object> = ChainableTestAPI<ExtraContext> &
+export type TestAPI<ExtraContext = object> = ChainableTestAPI<ExtraContext> &
   ExtendedAPI<ExtraContext> & {
     extend: <T extends Record<string, any> = object>(
       fixtures: Fixtures<T, ExtraContext>
-    ) => CustomAPI<{
+    ) => TestAPI<{
       [K in keyof T | keyof ExtraContext]: K extends keyof T
         ? T[K]
         : K extends keyof ExtraContext
@@ -424,7 +424,7 @@ export type CustomAPI<ExtraContext = object> = ChainableTestAPI<ExtraContext> &
     }>
   }
 
-export type TestAPI<ExtraContext = object> = CustomAPI<ExtraContext>
+export type { TestAPI as CustomAPI }
 
 export interface FixtureOptions {
   /**
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 910d6569aeca..cfd2be69d5ff 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1259,6 +1259,12 @@ importers:
         specifier: latest
         version: 9.2.1
 
+  test/dts-fixture:
+    devDependencies:
+      vitest:
+        specifier: workspace:*
+        version: link:../../packages/vitest
+
   test/global-setup:
     devDependencies:
       vitest:
diff --git a/test/dts-fixture/package.json b/test/dts-fixture/package.json
new file mode 100644
index 000000000000..265568018441
--- /dev/null
+++ b/test/dts-fixture/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "@vitest/test-dts-fixture",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "build": "rm -rf dist && tsc -p tsconfig.json",
+    "check": "tsc -p tsconfig.check.json",
+    "test": "pnpm build && pnpm check"
+  },
+  "devDependencies": {
+    "vitest": "workspace:*"
+  }
+}
diff --git a/test/dts-fixture/src/repro.ts b/test/dts-fixture/src/repro.ts
new file mode 100644
index 000000000000..dd15c27a142e
--- /dev/null
+++ b/test/dts-fixture/src/repro.ts
@@ -0,0 +1,7 @@
+import { test } from 'vitest'
+
+export const myTest = test.extend<{ now: number }>({
+  now: async ({}, use) => {
+    await use(Date.now())
+  },
+})
diff --git a/test/dts-fixture/tsconfig.check.json b/test/dts-fixture/tsconfig.check.json
new file mode 100644
index 000000000000..bd4257e82675
--- /dev/null
+++ b/test/dts-fixture/tsconfig.check.json
@@ -0,0 +1,12 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "types": [],
+    "strict": true,
+    "noEmit": true,
+    "verbatimModuleSyntax": true
+  },
+  "include": ["dist"]
+}
diff --git a/test/dts-fixture/tsconfig.json b/test/dts-fixture/tsconfig.json
new file mode 100644
index 000000000000..764098fa8e24
--- /dev/null
+++ b/test/dts-fixture/tsconfig.json
@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "ESNext",
+    "moduleResolution": "Bundler",
+    "strict": true,
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "dist",
+    "sourceMap": true,
+    "verbatimModuleSyntax": true
+  },
+  "include": ["src"]
+}