diff --git a/package.json b/package.json
index d9eb802f..10e51f6e 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "2.4.0",
   "description": "Simple, unobtrusive authentication for Fastify.",
   "main": "dist/index.js",
+  "type": "commonjs",
   "types": "dist/index.d.ts",
   "scripts": {
     "build": "rimraf ./dist && mkdir dist && tsc --outDir dist && git rev-parse HEAD > BUILD_SHA",