diff --git a/src/added.js b/src/added.js
index 0dd7d22..85e955f 100644
--- a/src/added.js
+++ b/src/added.js
@@ -1,4 +1,4 @@
-import { isEmpty, isObject, hasOwnProperty } from './utils';
+import { isEmpty, isObject, hasOwnProperty } from './utils.js';
 
 const addedDiff = (lhs, rhs) => {
 
diff --git a/src/arrayDiff.js b/src/arrayDiff.js
index dbe9b7d..17ad61f 100644
--- a/src/arrayDiff.js
+++ b/src/arrayDiff.js
@@ -1,4 +1,4 @@
-import { isDate, isEmpty, isObject, hasOwnProperty } from './utils';
+import { isDate, isEmpty, isObject, hasOwnProperty } from './utils.js';
 
 const diff = (lhs, rhs) => {
   if (lhs === rhs) return {}; // equal return no diff
diff --git a/src/deleted.js b/src/deleted.js
index 50feb17..74eb87e 100644
--- a/src/deleted.js
+++ b/src/deleted.js
@@ -1,4 +1,4 @@
-import { isEmpty, isObject, hasOwnProperty } from './utils';
+import { isEmpty, isObject, hasOwnProperty } from './utils.js';
 
 const deletedDiff = (lhs, rhs) => {
   if (lhs === rhs || !isObject(lhs) || !isObject(rhs)) return {};
diff --git a/src/detailed.js b/src/detailed.js
index 332ca67..3b36768 100644
--- a/src/detailed.js
+++ b/src/detailed.js
@@ -1,6 +1,6 @@
-import addedDiff from './added';
-import deletedDiff from './deleted';
-import updatedDiff from './updated';
+import addedDiff from './added.js';
+import deletedDiff from './deleted.js';
+import updatedDiff from './updated.js';
 
 const detailedDiff = (lhs, rhs) => ({
   added: addedDiff(lhs, rhs),
diff --git a/src/diff.js b/src/diff.js
index b433b14..dc7353c 100644
--- a/src/diff.js
+++ b/src/diff.js
@@ -1,4 +1,4 @@
-import { isDate, isEmptyObject, isObject, hasOwnProperty } from './utils';
+import { isDate, isEmptyObject, isObject, hasOwnProperty } from './utils.js';
 
 const diff = (lhs, rhs) => {
   if (lhs === rhs) return {}; // equal return no diff
diff --git a/src/index.js b/src/index.js
index 87337a1..d497af9 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,8 +1,8 @@
-import diff from './diff';
-import addedDiff from './added';
-import deletedDiff from './deleted';
-import updatedDiff from './updated';
-import detailedDiff from './detailed';
+import diff from './diff.js';
+import addedDiff from './added.js';
+import deletedDiff from './deleted.js';
+import updatedDiff from './updated.js';
+import detailedDiff from './detailed.js';
 
 export {
   addedDiff,
diff --git a/src/preserveArray.js b/src/preserveArray.js
index 8c817e4..90bf54b 100644
--- a/src/preserveArray.js
+++ b/src/preserveArray.js
@@ -1,4 +1,4 @@
-import { isObject, hasOwnProperty } from './utils';
+import { isObject, hasOwnProperty } from './utils.js';
 
 const getLargerArray = (l, r) => l.length > r.length ? l : r;
 
diff --git a/src/updated.js b/src/updated.js
index 8ab87ab..ce81249 100644
--- a/src/updated.js
+++ b/src/updated.js
@@ -1,4 +1,4 @@
-import { isDate, isEmptyObject, isObject, hasOwnProperty } from './utils';
+import { isDate, isEmptyObject, isObject, hasOwnProperty } from './utils.js';
 
 const updatedDiff = (lhs, rhs) => {
   if (lhs === rhs) return {};