diff --git a/example/basic/src/index.test.ts b/example/basic/src/index.test.ts
index 2e369bdd..18493e9b 100644
--- a/example/basic/src/index.test.ts
+++ b/example/basic/src/index.test.ts
@@ -3,7 +3,8 @@
 import index from './';
 
 describe('sum', () => {
-  it('works', () => {
-    expect(index()).toBe(11);
+  it('works', async () => {
+    const num = await index();
+    expect(num).toBe(11);
   });
 });
diff --git a/example/basic/test/index.test.ts b/example/basic/test/index.test.ts
index a9015067..dfa9bd02 100644
--- a/example/basic/test/index.test.ts
+++ b/example/basic/test/index.test.ts
@@ -1,7 +1,9 @@
+/// <reference types="jest" />
+
 import { sum } from '../src/utils/sum';
 
 describe('sum', () => {
-  it('works', () => {
+  it('works', async () => {
     expect(sum(1, 1)).toEqual(2);
   });
 });