diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c365752..29f1873e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,7 @@
 All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog].
 
-## Unreleased
+## 4.0 (released 2023-11-23)
 ### Breaking changes
 * The order of entries in `apheleia-mode-alist` is no longer as
   important. Specifically, if two different mode entries in
diff --git a/apheleia.el b/apheleia.el
index f4b0ebf8..7b7fe2d1 100644
--- a/apheleia.el
+++ b/apheleia.el
@@ -8,7 +8,7 @@
 ;; Keywords: tools
 ;; Package-Requires: ((emacs "27"))
 ;; SPDX-License-Identifier: MIT
-;; Version: 3.2
+;; Version: 4.0
 
 ;;; Commentary: