diff --git a/CHANGELOG.md b/CHANGELOG.md
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--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,5 @@
+# Revision history for wide-word-instances
+
+## 0.1 -- 2021-04-21
+
+* Initial version, with instances for `Binary` and `Serialise`.
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+3. Neither the name of the author nor the names of his contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/src/Data/WideWord/Instances.hs b/src/Data/WideWord/Instances.hs
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--- /dev/null
+++ b/src/Data/WideWord/Instances.hs
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+{-# LANGUAGE DeriveAnyClass        #-}
+{-# LANGUAGE StandaloneDeriving    #-}
+
+{-# OPTIONS_GHC -Wno-orphans #-}
+module Data.WideWord.Instances where
+
+import Codec.Serialise (Serialise)
+import Data.Binary     (Binary)
+
+import Data.WideWord
+
+deriving instance Binary Int128
+deriving instance Serialise Int128
+
+deriving instance Binary Word128
+deriving instance Serialise Word128
+
+deriving instance Binary Word256
+deriving instance Serialise Word256
diff --git a/wide-word-instances.cabal b/wide-word-instances.cabal
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--- /dev/null
+++ b/wide-word-instances.cabal
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+cabal-version:       2.4
+name:                wide-word-instances
+version:             0.1
+synopsis:            Instances for wide-word
+description:
+ This package provides extra instances for @wide-word@, that are currently
+ unsuitable for either @wide-word@ itself or the typeclass's own package,
+ because it would introduce too many dependencies.
+homepage:            https://github.com/infinity0/wide-word-instances
+bug-reports:         https://github.com/infinity0/wide-word-instances/issues
+license:             BSD-3-Clause
+license-file:        LICENSE
+author:              Ximin Luo
+maintainer:          infinity0@pwned.gg
+copyright:           (c) 2021 by Ximin Luo
+category:            Data, Numeric, Instances
+extra-source-files:  CHANGELOG.md
+tested-with:
+  GHC ==8.0.2
+   || ==8.2.2
+   || ==8.4.4
+   || ==8.6.5
+   || ==8.8.3
+   || ==8.10.4
+   || ==9.0.1
+
+library
+  default-language:    Haskell2010
+  ghc-options:         -Wall
+  hs-source-dirs:      src
+  build-depends:
+  -- boot libs, see https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/libraries/version-history
+      base                          >=4.9.0.0   && <5
+    , binary                        >=0.8.3.0   && <0.9
+    , serialise                     >=0.2.3.0   && <0.3
+    , wide-word                     >=0.1.1.0   && <0.2
+  exposed-modules:
+      Data.WideWord.Instances