diff --git a/Progress.js b/Progress.js
index 285fdce..6393a10 100644
--- a/Progress.js
+++ b/Progress.js
@@ -1,4 +1,4 @@
-import speedometer from './speedometer';
+import speedometer from './speedometer.js';
 
 export default class Progress {
   constructor(length, emitDelay = 1000) {
diff --git a/index.js b/index.js
index 66633ad..fed819a 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,4 @@
-import Progress from './Progress';
+import Progress from './Progress.js';
 
 export function isFetchProgressSupported() {
   return (