diff --git a/CHANGES.md b/CHANGES.md
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,10 @@
+0.3.3.0 (2018-06-15)
+====================
+
+-   Add Semigroup instances for some internal types. This improves GHC 8.4
+    compatibility.
+
+
 0.3.2.0 (2017-06-03)
 ====================
 
diff --git a/pinch.cabal b/pinch.cabal
--- a/pinch.cabal
+++ b/pinch.cabal
@@ -1,9 +1,11 @@
--- This file has been generated from package.yaml by hpack version 0.15.0.
+-- This file has been generated from package.yaml by hpack version 0.28.2.
 --
 -- see: https://github.com/sol/hpack
+--
+-- hash: 81e0ecf2f54c375e7fea61c471bd14781b8d75e4df2e4275e35022d78671ba9e
 
 name:           pinch
-version:        0.3.2.0
+version:        0.3.3.0
 cabal-version:  >= 1.10
 build-type:     Simple
 license:        BSD3
@@ -26,7 +28,6 @@
                 aims to provide an alternative implementation of Thrift for Haskell.
 category:       Development
 author:         Abhinav Gupta
-
 extra-source-files:
     bench/pinch-bench/Bench.hs
     bench/pinch-bench/pinch-bench.cabal
@@ -48,16 +49,17 @@
         src
     ghc-options: -Wall
     build-depends:
-        base >= 4.7 && < 5,
-        bytestring >= 0.10 && < 0.11,
-        containers >= 0.5 && < 0.6,
-        text >= 1.2 && < 1.3,
-        unordered-containers >= 0.2 && < 0.3,
-        vector >= 0.10 && < 0.13,
-        array >= 0.5,
-        deepseq >= 1.3 && < 1.5,
+        array >=0.5,
+        base >=4.7 && <5,
+        bytestring >=0.10 && <0.11,
+        containers >=0.5 && <0.6,
+        deepseq >=1.3 && <1.5,
         ghc-prim,
-        hashable >= 1.2 && < 1.3
+        hashable >=1.2 && <1.3,
+        semigroups >=0.18 && <0.19,
+        text >=1.2 && <1.3,
+        unordered-containers >=0.2 && <0.3,
+        vector >=0.10 && <0.13
     exposed-modules:
         Pinch
         Pinch.Internal.Builder
@@ -84,16 +86,17 @@
         tests
     ghc-options: -Wall
     build-depends:
-        base >= 4.7 && < 5,
-        bytestring >= 0.10 && < 0.11,
-        containers >= 0.5 && < 0.6,
-        text >= 1.2 && < 1.3,
-        unordered-containers >= 0.2 && < 0.3,
-        vector >= 0.10 && < 0.13,
-        hspec >= 2.0,
-        hspec-discover >= 2.1,
+        QuickCheck >=2.5,
+        base >=4.7 && <5,
+        bytestring >=0.10 && <0.11,
+        containers >=0.5 && <0.6,
+        hspec >=2.0,
+        hspec-discover >=2.1,
         pinch,
-        QuickCheck >= 2.5
+        semigroups >=0.18 && <0.19,
+        text >=1.2 && <1.3,
+        unordered-containers >=0.2 && <0.3,
+        vector >=0.10 && <0.13
     other-modules:
         Pinch.Arbitrary
         Pinch.Expectations
@@ -108,4 +111,5 @@
         Pinch.Internal.ValueSpec
         Pinch.Protocol.BinarySpec
         Pinch.Protocol.CompactSpec
+        Paths_pinch
     default-language: Haskell2010
diff --git a/src/Pinch/Internal/Builder.hs b/src/Pinch/Internal/Builder.hs
--- a/src/Pinch/Internal/Builder.hs
+++ b/src/Pinch/Internal/Builder.hs
@@ -27,13 +27,10 @@
     , byteString
     ) where
 
-#if __GLASGOW_HASKELL__ < 709
-import Data.Monoid
-#endif
-
 import Data.ByteString              (ByteString)
 import Data.ByteString.Builder.Prim ((>*<))
 import Data.Int
+import Data.Semigroup
 import Data.Word                    (Word8)
 import Foreign.ForeignPtr           (withForeignPtr)
 import Foreign.Ptr                  (Ptr, plusPtr)
@@ -56,6 +53,10 @@
 {-# INLINE [1] append #-}
     -- Don't inline append until phase 1. This ensures that the
     -- append/primFixed* rules have a chance to fire.
+
+instance Semigroup Builder where
+    (<>) = append
+    sconcat = foldr (<>) mempty
 
 instance Monoid Builder where
     {-# INLINE mempty #-}
diff --git a/src/Pinch/Internal/FoldList.hs b/src/Pinch/Internal/FoldList.hs
--- a/src/Pinch/Internal/FoldList.hs
+++ b/src/Pinch/Internal/FoldList.hs
@@ -34,7 +34,7 @@
 import Control.DeepSeq (NFData (..))
 import Data.Hashable   (Hashable (..))
 import Data.List       (intercalate)
-import Data.Monoid
+import Data.Semigroup
 import Data.Typeable   (Typeable)
 
 import qualified Control.Monad    as M
@@ -96,7 +96,7 @@
     {-# INLINE fmap #-}
 
 instance F.Foldable FoldList where
-    foldMap f (FoldList l) = l (\r a -> r <> f a) mempty
+    foldMap f (FoldList l) = l (\r a -> r `mappend` f a) mempty
     {-# INLINE foldMap #-}
 
     foldl' f r (FoldList l) = l f r
@@ -119,10 +119,14 @@
 instance Hashable a => Hashable (FoldList a) where
     hashWithSalt s (FoldList l) = l hashWithSalt s
 
+instance Semigroup (FoldList a) where
+    FoldList f1 <> FoldList f2 =
+        FoldList $ \cons nil -> f2 cons (f1 cons nil)
+    {-# INLINE (<>) #-}
+
 instance Monoid (FoldList a) where
     mempty = FoldList (\_ r -> r)
     {-# INLINE mempty #-}
 
-    FoldList f1 `mappend` FoldList f2 =
-        FoldList $ \cons nil -> f2 cons (f1 cons nil)
+    FoldList f1 `mappend` FoldList f2 = FoldList $ \cons nil -> f2 cons (f1 cons nil)
     {-# INLINE mappend #-}
diff --git a/src/Pinch/Internal/Generic.hs b/src/Pinch/Internal/Generic.hs
--- a/src/Pinch/Internal/Generic.hs
+++ b/src/Pinch/Internal/Generic.hs
@@ -47,10 +47,10 @@
 
 #if __GLASGOW_HASKELL__ < 709
 import Data.Foldable    (Foldable)
-import Data.Monoid      (Monoid)
 import Data.Traversable (Traversable)
 #endif
 
+import Data.Semigroup
 import Control.Applicative
 import Control.DeepSeq     (NFData)
 import Data.Proxy          (Proxy (..))
@@ -126,7 +126,7 @@
 -- new data type.
 newtype Field (n :: Nat) a = Field a
   deriving
-    (Bounded, Eq, Enum, Foldable, Functor, Generic, Monoid, NFData, Ord, Show,
+    (Bounded, Eq, Enum, Foldable, Functor, Generic, Semigroup, Monoid, NFData, Ord, Show,
      Traversable, Typeable)
 
 -- | Gets the current value of a field.