diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,3 @@
+# 0.1.1.0
+
+- Added Semigroup Nat instance, for compatibility with GHC 8.4
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,5 +1,4 @@
 Copyright 2017 Li-yao Xia
-Copyright 2017 Li-yao Xia
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of
 this software and associated documentation files (the "Software"), to deal in
diff --git a/boltzmann-samplers.cabal b/boltzmann-samplers.cabal
--- a/boltzmann-samplers.cabal
+++ b/boltzmann-samplers.cabal
@@ -1,5 +1,5 @@
 name:                boltzmann-samplers
-version:             0.1.0.0
+version:             0.1.1.0
 synopsis:            Uniform random generators
 description:
 
@@ -16,8 +16,11 @@
 maintainer:          lysxia@gmail.com
 category:            Data, Generic, Random
 build-type:          Simple
-extra-source-files:  README.md
+extra-source-files:
+  README.md
+  CHANGELOG.md
 cabal-version:       >=1.10
+tested-with:         GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.1
 
 flag test
   Description:
@@ -38,7 +41,7 @@
     Boltzmann.Species
   build-depends:
     ad,
-    base >= 4.9 && < 5,
+    base >= 4.8 && < 5,
     containers,
     hashable,
     hmatrix,
@@ -49,6 +52,9 @@
     QuickCheck,
     transformers,
     vector
+  if impl(ghc < 8.0)
+    build-depends:
+      semigroups
   default-language:    Haskell2010
 
 source-repository head
diff --git a/src/Boltzmann/Data/Oracle.hs b/src/Boltzmann/Data/Oracle.hs
--- a/src/Boltzmann/Data/Oracle.hs
+++ b/src/Boltzmann/Data/Oracle.hs
@@ -21,10 +21,12 @@
 import Data.HashMap.Lazy ( HashMap )
 import qualified Data.HashMap.Lazy as HashMap
 import Data.Maybe ( fromJust, isJust )
-import Data.Monoid
+import Data.Monoid hiding ((<>))
+import Data.Semigroup
 import qualified Data.Vector as V
 import GHC.Generics ( Generic )
 import Numeric.AD
+
 import Boltzmann.Data.Common
 import Boltzmann.Data.Types
 import Boltzmann.Solver
@@ -97,10 +99,13 @@
 data Nat = Zero | Succ Nat
   deriving (Eq, Ord, Show)
 
+instance Semigroup Nat where
+  (<>) (Succ n) = Succ . (<>) n
+  (<>) Zero = id
+
 instance Monoid Nat where
   mempty = Zero
-  mappend (Succ n) = Succ . mappend n
-  mappend Zero = id
+  mappend = (<>)
 
 natToInt :: Nat -> Int
 natToInt Zero = 0