diff --git a/CHANGES.md b/CHANGES.md
index 1d04184f..5a03323a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,4 +1,4 @@
-## dev (Unreleased)
+## v1.0.0 (May 2022)
 
 - Add selective to Either, Options, Result and Try [**@d-plaindoux**](https://github.com/d-plaindoux)
 - Add specialized interpreters/handlers for `Free` and `Freer` monads [**@xhtmlboi**](https://github.com/xhtmlboi)
diff --git a/preface.opam b/preface.opam
index aa5e016e..181da930 100644
--- a/preface.opam
+++ b/preface.opam
@@ -1,5 +1,5 @@
 opam-version: "2.0"
-version: "dev"
+version: "1.0.0"
 
 maintainer: "xaviervdw@gmail.com"
 authors: [