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).
 
+## 0.13.4
+### Added
+- Support for Bitcoin Cash May 2020 hard fork.
+
 ## 0.13.3
 ### Changed
 - Improve code and documentation organisation.
diff --git a/haskoin-core.cabal b/haskoin-core.cabal
--- a/haskoin-core.cabal
+++ b/haskoin-core.cabal
@@ -1,13 +1,13 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.31.2.
+-- This file has been generated from package.yaml by hpack version 0.33.0.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 68a2e91c88690c0a8574a9151c0fd55c9a9a6d0ae9693909ebc8f1716eacb5d5
+-- hash: ee5ff7456453fe4afdfd49adb164df9da4ea7368e9f8a04d4d4315b2d29a14ab
 
 name:           haskoin-core
-version:        0.13.3
+version:        0.13.4
 synopsis:       Bitcoin & Bitcoin Cash library for Haskell
 description:    Haskoin Core is a complete Bitcoin and Bitcoin Cash library of functions and data types for Haskell developers.
 category:       Bitcoin, Finance, Network
diff --git a/src/Haskoin/Script/Common.hs b/src/Haskoin/Script/Common.hs
--- a/src/Haskoin/Script/Common.hs
+++ b/src/Haskoin/Script/Common.hs
@@ -214,6 +214,8 @@
       -- Bitcoin Cash Nov 2018 hard fork
     | OP_CHECKDATASIG
     | OP_CHECKDATASIGVERIFY
+      -- Bitcoin Cash May 2020 hard fork
+    | OP_REVERSEBYTES
       -- Other
     | OP_PUBKEYHASH
     | OP_PUBKEY
@@ -367,6 +369,9 @@
             | op == 0xba = return OP_CHECKDATASIG
             | op == 0xbb = return OP_CHECKDATASIGVERIFY
 
+            -- Bitcoin Cash May 2020 hard fork
+            | op == 0xbc = return OP_REVERSEBYTES
+
             -- Constants
             | op == 0xfd = return OP_PUBKEYHASH
             | op == 0xfe = return OP_PUBKEY
@@ -533,6 +538,9 @@
         -- Bitcoin Cash Nov 2018 hard fork
         OP_CHECKDATASIG      -> putWord8 0xba
         OP_CHECKDATASIGVERIFY -> putWord8 0xbb
+
+        -- Bitcoin Cash May 2020 hard fork
+        OP_REVERSEBYTES      -> putWord8 0xbc
 
 
 -- | Check whether opcode is only data.
diff --git a/test/Haskoin/ScriptSpec.hs b/test/Haskoin/ScriptSpec.hs
--- a/test/Haskoin/ScriptSpec.hs
+++ b/test/Haskoin/ScriptSpec.hs
@@ -10,7 +10,6 @@
 import           Data.List
 import           Data.Map.Strict         (singleton)
 import           Data.Maybe
-import           Data.Monoid             ((<>))
 import           Data.Serialize          as S
 import           Data.String
 import           Data.String.Conversions (cs)
diff --git a/test/Haskoin/Test/Script.hs b/test/Haskoin/Test/Script.hs
--- a/test/Haskoin/Test/Script.hs
+++ b/test/Haskoin/Test/Script.hs
@@ -149,6 +149,11 @@
         , return OP_NOP8
         , return OP_NOP9
         , return OP_NOP10
+        -- Bitcoin Cash Nov 2018 hard fork
+        , return OP_CHECKDATASIG
+        , return OP_CHECKDATASIGVERIFY
+        -- Bitcoin Cash May 2020 hard fork
+        , return OP_REVERSEBYTES
         -- Other
         , return OP_PUBKEYHASH
         , return OP_PUBKEY