diff --git a/CHANGELOG.md b/CHANGELOG.md
index 34039c5..7a7304c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic versioning](http://semver.org/).
 
+## [1.4.0] - 2023-09-27
+
+- introduce `OppositeSemigroup` and `OppositMonoid`
+- do not flip arguments on `ListL/ConcatenationMonoid`
+
 ## [1.3.0] - 2023-08-23
 
 - introduce `Alt` and `Plus` typeclasses