diff --git a/Data/ByteString/FastBuilder/Internal.hs b/Data/ByteString/FastBuilder/Internal.hs
--- a/Data/ByteString/FastBuilder/Internal.hs
+++ b/Data/ByteString/FastBuilder/Internal.hs
@@ -3,7 +3,6 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE CPP #-}
 
 -- | This is an internal module; its interface is unstable.
 module Data.ByteString.FastBuilder.Internal
@@ -126,7 +125,7 @@
   {-# INLINE mempty #-}
   mappend = (<>)
   {-# INLINE mappend #-}
-  mconcat xs = foldr mappend mempty xs
+  mconcat = foldr mappend mempty
   {-# INLINE mconcat #-}
 
 -- | 'fromString' = 'stringUtf8'
@@ -381,7 +380,7 @@
 
 -- | Run the given suspended builder using a new thread.
 toBufferWriter :: MVar Request -> MVar Response -> Ptr Word8 -> X.BufferWriter
-toBufferWriter !reqV !respV thunk buf0 sz0 = E.mask_ $ do
+toBufferWriter !reqV !respV thunk buf0 sz0 = E.mask_ $
   writer Nothing buf0 sz0
   where
     writer !maybeBuilderTid !buf !sz = do
@@ -492,7 +491,7 @@
 
 -- | Turn a value of type @a@ into a 'Builder', using the given 'PI.BoundedPrim'.
 primBounded :: PI.BoundedPrim a -> a -> Builder
-primBounded prim x = write $ writeBoundedPrim prim x
+primBounded prim = write . writeBoundedPrim prim
 {-# INLINE primBounded #-}
 
 -- | Turn a 'Write' into a 'Builder'.
@@ -515,19 +514,19 @@
 
 -- | Turn a value of type @a@ into a 'Builder', using the given 'PI.FixedPrim'.
 primFixed :: PI.FixedPrim a -> a -> Builder
-primFixed prim = \x -> primBounded (PI.toB prim) x
+primFixed prim = primBounded (PI.toB prim)
 {-# INLINE primFixed #-}
 
 -- | Turn a list of values of type @a@ into a 'Builder', using the given
 -- 'PI.BoundedPrim'.
 primMapListBounded :: PI.BoundedPrim a -> [a] -> Builder
-primMapListBounded prim = \xs -> mconcat $ map (primBounded prim) xs
+primMapListBounded prim = mconcat . map (primBounded prim)
 {-# INLINE primMapListBounded #-}
 
 -- | Turn a list of values of type @a@ into a 'Builder', using the given
 -- 'PI.FixedPrim'.
 primMapListFixed :: PI.FixedPrim a -> [a] -> Builder
-primMapListFixed prim = \xs -> primMapListBounded (PI.toB prim) xs
+primMapListFixed prim = primMapListBounded (PI.toB prim)
 {-# INLINE primMapListFixed #-}
 
 -- | Turn a 'S.ByteString' to a 'Builder'.
@@ -772,9 +771,9 @@
 -- | Throw a 'ChunkOverflowException' and switches to a 'ThreadedSink'.
 chunkOverflow :: IORef DynamicSink -> Int -> S.ByteString -> BuildM ()
 chunkOverflow !dRef !minSize !chunk = do
-  myTid <- io $ myThreadId
-  reqV <- io $ newEmptyMVar
-  respV <- io $ newEmptyMVar
+  myTid <- io myThreadId
+  reqV <- io newEmptyMVar
+  respV <- io newEmptyMVar
   io $ E.throwTo myTid $ ChunkOverflowException chunk reqV respV minSize
   io $ writeIORef dRef $ ThreadedSink reqV respV
   handleRequest reqV
diff --git a/benchmarks/aeson/HashMapExts.hs b/benchmarks/aeson/HashMapExts.hs
--- a/benchmarks/aeson/HashMapExts.hs
+++ b/benchmarks/aeson/HashMapExts.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE QuasiQuotes #-}
-{-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE MagicHash #-}
 {-# LANGUAGE UnboxedTuples #-}
 module HashMapExts where
diff --git a/benchmarks/map.hs b/benchmarks/map.hs
--- a/benchmarks/map.hs
+++ b/benchmarks/map.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE DeriveFunctor #-}
 import Control.Concurrent
 import Criterion.Main
 import qualified Data.IntMap as IM
diff --git a/fast-builder.cabal b/fast-builder.cabal
--- a/fast-builder.cabal
+++ b/fast-builder.cabal
@@ -1,5 +1,5 @@
 name:                fast-builder
-version:             0.1.0.0
+version:             0.1.0.1
 synopsis:            Fast ByteString Builder
 description:         An efficient implementation of ByteString builder. It should be faster than
                      the standard implementation in most cases.
@@ -16,7 +16,7 @@
 extra-source-files:  benchmarks/aeson/*.hs
                      benchmarks/aeson/*.json
 cabal-version:       >=1.10
-tested-with:         GHC >= 7.10.1 && < 8.1
+tested-with:         GHC == 8.2.2, GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.1
 
 library
   exposed-modules:     Data.ByteString.FastBuilder,
@@ -25,10 +25,10 @@
   other-modules:       Data.ByteString.FastBuilder.Internal.Prim
 
   -- other-extensions:
-  build-depends:       base >= 4.8 && < 4.13, bytestring >= 0.10.6.0, ghc-prim
+  build-depends:       base >= 4.8 && < 4.14, bytestring >= 0.10.6.0, ghc-prim
   -- hs-source-dirs:
   default-language:    Haskell2010
-  ghc-options:         -Wall -g
+  ghc-options:         -Wall
 
 benchmark aeson
   type:                exitcode-stdio-1.0