diff --git a/esm.js b/esm.js
index 9a02fa6..a5b1ea3 100644
--- a/esm.js
+++ b/esm.js
@@ -2,7 +2,7 @@
 
 module.exports = {
   rules: {
-    'import/extensions': 0,
+    'import/extensions': ['error', 'always'],
   },
   extends: ['@wfcd'],
   parser: '@babel/eslint-parser',