diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9d0c8455..ad52e773 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,14 +1,18 @@
-# Changelog
-
 ## Unreleased
+
+## 4.0.0
+
+### Breaking
+- BREAKING: drop support for end-of-life Ruby versions 2.7 and 3.0. The minimum Ruby version is now 3.1.
+- BREAKING: drop support for IE8
 - Upgrade to govuk-frontend v5.7.1 and introduce new Javascript entry point
-  BREAKING: drop support for IE8
 
-You need to
+To upgrade you need to:
   - create a `govuk_frontend.js` file your project’s `source/assets/javascripts` directory
   - add `//= require govuk_frontend_all` into it
 
-- BREAKING: drop support for end-of-life Ruby versions 2.7 and 3.0. The minimum Ruby version is now 3.1.
+### Fixes
+
 - Update gem dependencies.
 - Declare some missing indirect dependencies to prepare for Ruby 3.4. This also resolves some warnings about this at build time.
 - Remove aria-hidden from search label to let assistive technologies see its accessible name
diff --git a/lib/govuk_tech_docs/version.rb b/lib/govuk_tech_docs/version.rb
index 39c17cdc..4f2dcb9a 100644
--- a/lib/govuk_tech_docs/version.rb
+++ b/lib/govuk_tech_docs/version.rb
@@ -1,3 +1,3 @@
 module GovukTechDocs
-  VERSION = "3.5.0".freeze
+  VERSION = "4.0.0".freeze
 end