diff --git a/package.json b/package.json
index e7a693a..dde8902 100644
--- a/package.json
+++ b/package.json
@@ -10,6 +10,7 @@
     "lib",
     "data-source"
   ],
+  "sideEffects": false,
   "keywords": [
     "cityData"
   ],