diff --git a/package-lock.json b/package-lock.json
index 210ec862e..6dd05f0ad 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "sinon",
-  "version": "8.1.1",
+  "version": "9.0.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 8621bbf70..d9206f789 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "sinon",
   "description": "JavaScript test spies, stubs and mocks.",
-  "version": "8.1.1",
+  "version": "9.0.0",
   "homepage": "https://sinonjs.org/",
   "author": "Christian Johansen",
   "repository": {