diff --git a/rollup.config.js b/rollup.config.js
index 9dc9b09..1297eab 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -8,7 +8,7 @@ export default {
       format: 'cjs',
     },
     {
-      file: 'dist/index.js',
+      file: 'dist/index.mjs',
       format: 'esm',
     },
   ],