diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,10 @@
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## 0.20.4
+### Fixed
+- Add missing case for witness version.
+
 ## 0.20.3
 ### Fixed
 - Allow unknown inv types.
diff --git a/haskoin-core.cabal b/haskoin-core.cabal
--- a/haskoin-core.cabal
+++ b/haskoin-core.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 51a1645e2f8c2dc54a6cc91c03a262683a314702f2ffbc182667967b50e88f6f
+-- hash: d57876572e143601ab9185c42f47f703460c4e8396b846f805068a5cff8fec3e
 
 name:           haskoin-core
-version:        0.20.3
+version:        0.20.4
 synopsis:       Bitcoin & Bitcoin Cash library for Haskell
 description:    Please see the README on GitHub at <https://github.com/haskoin/haskoin-core#readme>
 category:       Bitcoin, Finance, Network
diff --git a/src/Haskoin/Address.hs b/src/Haskoin/Address.hs
--- a/src/Haskoin/Address.hs
+++ b/src/Haskoin/Address.hs
@@ -19,6 +19,7 @@
       Address(..)
     , isPubKeyAddress
     , isScriptAddress
+    , isWitnessAddress
     , isWitnessPubKeyAddress
     , isWitnessScriptAddress
     , addrToText
diff --git a/src/Haskoin/Keys/Common.hs b/src/Haskoin/Keys/Common.hs
--- a/src/Haskoin/Keys/Common.hs
+++ b/src/Haskoin/Keys/Common.hs
@@ -34,7 +34,6 @@
     , toWif
     ) where
 
-import           Control.Applicative     ((<|>))
 import           Control.DeepSeq
 import           Control.Monad           (guard, mzero, (<=<))
 import           Crypto.Secp256k1
@@ -80,7 +79,7 @@
 
 instance FromJSON PubKeyI where
     parseJSON = withText "PubKeyI" $
-        maybe mzero return . (eitherToMaybe . runGetS deserialize =<<) . decodeHex
+        maybe mzero return . ((eitherToMaybe . runGetS deserialize) <=< decodeHex)
 
 instance Serial PubKeyI where
     deserialize = s >>= \case
diff --git a/src/Haskoin/Network/Common.hs b/src/Haskoin/Network/Common.hs
--- a/src/Haskoin/Network/Common.hs
+++ b/src/Haskoin/Network/Common.hs
@@ -493,7 +493,7 @@
         go 0xff = getWord64le
         go 0xfe = fromIntegral <$> getWord32le
         go 0xfd = fromIntegral <$> getWord16le
-        go x    = fromIntegral <$> return x
+        go x    = return $ fromIntegral x
 
     serialize (VarInt x)
         | x < 0xfd =
diff --git a/src/Haskoin/Script/Standard.hs b/src/Haskoin/Script/Standard.hs
--- a/src/Haskoin/Script/Standard.hs
+++ b/src/Haskoin/Script/Standard.hs
@@ -20,6 +20,7 @@
     , isPayPKHash
     , isPayMulSig
     , isPayScriptHash
+    , isPayWitness
     , isPayWitnessPKHash
     , isPayWitnessScriptHash
     , isDataCarrier
@@ -56,7 +57,7 @@
 import           Data.Function          (on)
 import           Data.Hashable
 import           Data.List              (sortBy)
-import           Data.Maybe             (fromJust, isJust, isNothing)
+import           Data.Maybe             (fromJust, isJust)
 import           Data.Word              (Word8)
 import           GHC.Generics           (Generic)
 import           Haskoin.Constants
@@ -189,6 +190,7 @@
 witnessVersionOp 14 = Just OP_14
 witnessVersionOp 15 = Just OP_15
 witnessVersionOp 16 = Just OP_16
+witnessVersionOp _ = Nothing
 
 opWitnessVersion :: ScriptOp -> Maybe Word8
 opWitnessVersion OP_0  = Just 0