diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for commutative-semigroups
 
-## Unreleased
+## 0.0.1.0 -- 2021-01-28
+
+- Add instance for `Maybe`.
+
+## 0.0.0.0 -- 2021-01-06
 
 Initial version, created from `groups` package.
diff --git a/ReadMe.md b/ReadMe.md
--- a/ReadMe.md
+++ b/ReadMe.md
@@ -1,6 +1,6 @@
 # Commutative Semigroup
 
-[![Haskell](https://img.shields.io/badge/language-Haskell-orange.svg)](https://haskell.org) [![Hackage](https://img.shields.io/hackage/v/commutative-semigroup.svg)](https://hackage.haskell.org/package/commutative-semigroup) [![Hackage CI](https://matrix.hackage.haskell.org/api/v2/packages/commutative-semigroup/badge)](https://matrix.hackage.haskell.org/#/package/commutative-semigroup)  [![BSD3 License](https://img.shields.io/badge/license-BSD3-blue.svg)](https://github.com/reflex-frp/commutative-semigroup/LICENSE)
+[![Haskell](https://img.shields.io/badge/language-Haskell-orange.svg)](https://haskell.org) [![Hackage](https://img.shields.io/hackage/v/commutative-semigroups.svg)](https://hackage.haskell.org/package/commutative-semigroups) [![Hackage CI](https://matrix.hackage.haskell.org/api/v2/packages/commutative-semigroups/badge)](https://matrix.hackage.haskell.org/#/package/commutative-semigroups)  [![BSD3 License](https://img.shields.io/badge/license-BSD3-blue.svg)](https://github.com/reflex-frp/commutative-semigroups/LICENSE)
 
 A commutative semigroup is a semigroup where the order of arguments to mappend does not matter.
 
diff --git a/commutative-semigroups.cabal b/commutative-semigroups.cabal
--- a/commutative-semigroups.cabal
+++ b/commutative-semigroups.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.4
 name:                commutative-semigroups
-version:             0.0.0.0
+version:             0.0.1.0
 synopsis:            Commutative semigroups
 description:
   A commutative semigroup is a semigroup where the order of arguments to mappend does not matter.
diff --git a/src/Data/Semigroup/Commutative.hs b/src/Data/Semigroup/Commutative.hs
--- a/src/Data/Semigroup/Commutative.hs
+++ b/src/Data/Semigroup/Commutative.hs
@@ -37,6 +37,9 @@
 -- | Trivial commutative semigroup.
 instance Commutative ()
 
+-- | @since 0.0.1.0
+instance Commutative a => Commutative (Maybe a)
+
 instance Num a => Commutative (Sum a)
 
 instance Fractional a => Commutative (Product a)