diff --git a/package.json b/package.json
index 1b8dc76afc3cf5890cc3693c2975577fd3117dd6..d215ae8677dc8b82c0f4d9b9af557b860ac16292 100644
--- a/package.json
+++ b/package.json
@@ -5,6 +5,7 @@
   "main": "dist/acorn.js",
   "types": "dist/acorn.d.ts",
   "module": "dist/acorn.mjs",
+  "sideEffects": false,
   "exports": {
     ".": [
       {
