diff --git a/Data/Functor/Contravariant.hs b/Data/Functor/Contravariant.hs
--- a/Data/Functor/Contravariant.hs
+++ b/Data/Functor/Contravariant.hs
@@ -36,8 +36,10 @@
   ) where
 
 import Control.Applicative
+import Control.Category
 import Data.Functor.Product
 import Data.Functor.Constant
+import Prelude hiding ((.),id)
 
 -- | Any instance should be subject to the following laws:
 --
@@ -95,6 +97,10 @@
 
 -- | Dual function arrows.
 newtype Op a b = Op { getOp :: b -> a }
+
+instance Category Op where
+  id = Op id
+  Op f . Op g = Op (g . f)
 
 instance Contravariant (Op a) where
   contramap f g = Op (getOp g . f)
diff --git a/contravariant.cabal b/contravariant.cabal
--- a/contravariant.cabal
+++ b/contravariant.cabal
@@ -1,6 +1,6 @@
 name:          contravariant
 category:      Control, Data
-version:       0.1.3
+version:       0.2
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
@@ -18,10 +18,10 @@
   location: git://github.com/ekmett/contravariant.git
 
 library
-  build-depends: 
+  build-depends:
     base < 5,
     transformers >= 0.2.2 && < 0.3
-  exposed-modules: 
+  exposed-modules:
     Data.Functor.Contravariant
     Data.Functor.Contravariant.Compose
-  ghc-options: -Wall 
+  ghc-options: -Wall