diff --git a/src/forEach.spec.js b/src/forEach.spec.js
index 797625e..aecb3b3 100644
--- a/src/forEach.spec.js
+++ b/src/forEach.spec.js
@@ -76,7 +76,7 @@ describe('asyncForEach()', () => {
   });
 
   it('returns undefined', async () => {
-    const [, pushDuplicate] = makePushDuplicate();
+    const [, pushDuplicate] = makePushDuplicateInRandomTime();
     const mapper = jest.fn().mockImplementation(pushDuplicate);
 
     const result = await asyncForEach(inputArr, mapper);
diff --git a/src/forEach_strict.spec.js b/src/forEach_strict.spec.js
index 98bfebf..20a73cb 100644
--- a/src/forEach_strict.spec.js
+++ b/src/forEach_strict.spec.js
@@ -102,7 +102,7 @@ describe('asyncForEachStrict()', () => {
   });
 
   it('returns undefined', async () => {
-    const [, pushDuplicate] = makePushDuplicate();
+    const [, pushDuplicate] = makePushDuplicateInRandomTime();
     const mapper = jest.fn().mockImplementation(pushDuplicate);
 
     const result = await asyncForEachStrict(inputArr, mapper);