diff --git a/package.json b/package.json
index f436aa5d..1e88d0c7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "webextension-polyfill",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "description": "A lightweight polyfill library for Promise-based WebExtension APIs in Chrome.",
   "main": "dist/browser-polyfill.js",
   "files": [