diff --git a/package.json b/package.json
index 9470ef5..cd580b2 100644
--- a/package.json
+++ b/package.json
@@ -3,13 +3,13 @@
   "version": "0.0.3",
   "description": "High performance Zstandard (de)compression",
   "main": "./lib/index.js",
-  "module": "./esm/index.js",
+  "module": "./esm/index.mjs",
   "types": "./lib/index.d.ts",
   "unpkg": "./umd/index.js",
   "jsdelivr": "./umd/index.js",
   "exports": {
     ".": {
-      "import": "./esm/index.js",
+      "import": "./esm/index.mjs",
       "require": "./lib/index.js"
     }
   },
diff --git a/scripts/rewriteBuilds.ts b/scripts/rewriteBuilds.ts
index 5e9ada4..91b5f0f 100644
--- a/scripts/rewriteBuilds.ts
+++ b/scripts/rewriteBuilds.ts
@@ -1,4 +1,4 @@
-import { readFileSync, writeFileSync } from 'fs';
+import { readFileSync, writeFileSync, unlinkSync } from 'fs';
 import { join } from 'path';
 const atClass = /\/\*\* \@class \*\//g, pure = '/*#__PURE__*/';
 
@@ -9,5 +9,7 @@ writeFileSync(libIndex, readFileSync(libIndex, 'utf-8')
   .replace(/exports\.(.*) = void 0;\n/, '')
 );
 
-const esmIndex = join(__dirname, '..', 'esm', 'index.js')
-writeFileSync(esmIndex, readFileSync(esmIndex, 'utf-8').replace(atClass, pure));
\ No newline at end of file
+const esm = join(__dirname, '..', 'esm');
+const esmIndex = join(esm, 'index.js');
+writeFileSync(join(esm, 'index.mjs'), readFileSync(esmIndex, 'utf-8').replace(atClass, pure));
+unlinkSync(esmIndex);
\ No newline at end of file