diff --git a/src/IndexError.js b/src/IndexError.js
index 31bbb21..76db9bc 100644
--- a/src/IndexError.js
+++ b/src/IndexError.js
@@ -1,3 +1,3 @@
-import customError from './customError' ;
+import customError from "./customError.js" ;
 
 export default customError('IndexError') ;
diff --git a/src/KeyError.js b/src/KeyError.js
index d75f3fb..1ad9582 100644
--- a/src/KeyError.js
+++ b/src/KeyError.js
@@ -1,3 +1,3 @@
-import customError from './customError' ;
+import customError from "./customError.js" ;
 
 export default customError('KeyError') ;
diff --git a/src/NotImplementedError.js b/src/NotImplementedError.js
index 8bf90c9..e2ab693 100644
--- a/src/NotImplementedError.js
+++ b/src/NotImplementedError.js
@@ -1,3 +1,3 @@
-import customError from './customError' ;
+import customError from "./customError.js" ;
 
 export default customError('NotImplementedError') ;
diff --git a/src/StopIteration.js b/src/StopIteration.js
index 5f66673..58a9eb1 100644
--- a/src/StopIteration.js
+++ b/src/StopIteration.js
@@ -1,3 +1,3 @@
-import customError from './customError' ;
+import customError from "./customError.js" ;
 
 export default customError('StopIteration') ;
diff --git a/src/ValueError.js b/src/ValueError.js
index 24a0b97..c8024a1 100644
--- a/src/ValueError.js
+++ b/src/ValueError.js
@@ -1,3 +1,3 @@
-import customError from './customError' ;
+import customError from "./customError.js" ;
 
 export default customError('ValueError') ;
diff --git a/src/customError.js b/src/customError.js
index ce162ab..58c4ffb 100644
--- a/src/customError.js
+++ b/src/customError.js
@@ -1,5 +1,5 @@
-import Error from './Error' ;
-import extendError from './extendError' ;
+import Error from "./Error.js" ;
+import extendError from "./extendError.js" ;
 
 const customError = name => extendError( Error , name ) ;
 export default customError;
diff --git a/test/src/error.js b/test/src/error.js
index b0a1993..a83b0c3 100644
--- a/test/src/error.js
+++ b/test/src/error.js
@@ -9,7 +9,7 @@ import {
 	NotImplementedError ,
 	ValueError ,
 	StopIteration ,
-} from '../../src' ;
+} from "../../src/index.js" ;
 
 const errors = [
 	Error ,