diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+v0.3.1.1
+
+  * Merged [Typetetris](https://github.com/typetetris) PR, making the package compatible with GHC 8.4+
+
 v0.3.1
 
  * Added the satisfy function
diff --git a/fastparser.cabal b/fastparser.cabal
--- a/fastparser.cabal
+++ b/fastparser.cabal
@@ -1,5 +1,5 @@
 name:                fastparser
-version:             0.3.1
+version:             0.3.1.1
 synopsis:            A fast, but bare bones, bytestring parser combinators library.
 description:         Please see README.md
 homepage:            https://github.com/bartavelle/fastparser#readme
@@ -28,6 +28,8 @@
                      , transformers      >= 0.4
   ghc-options:         -O2 -Wall
   default-language:    Haskell2010
+  if !impl(ghc >= 8.0)
+    build-depends: semigroups == 0.18.*
 
 source-repository head
   type:     git
diff --git a/src/ByteString/Parser/Fast.hs b/src/ByteString/Parser/Fast.hs
--- a/src/ByteString/Parser/Fast.hs
+++ b/src/ByteString/Parser/Fast.hs
@@ -76,7 +76,7 @@
 import Data.Thyme
 import Data.Thyme.Time.Core
 import Lens.Micro
-import Data.Monoid
+import Data.Semigroup
 import qualified Data.ByteString.Lex.Fractional as L
 import Control.Monad.Codensity (Codensity, lowerCodensity)
 import Control.Monad.Trans.Class (lift)
@@ -132,9 +132,12 @@
   , errorExpected   :: !(Set ErrorItem)
   } deriving (Show, Eq)
 
+instance Semigroup ParseError where
+  (<>) (ParseError u1 e1) (ParseError u2 e2) = ParseError (mappend u1 u2) (mappend e1 e2)
+
 instance Monoid ParseError where
   mempty = ParseError mempty mempty
-  mappend (ParseError u1 e1) (ParseError u2 e2) = ParseError (mappend u1 u2) (mappend e1 e2)
+  mappend = (<>)
 
 -- | An error representing the unexpected end of input.
 ueof :: ParseError