diff --git a/Data/Functor/Contravariant.hs b/Data/Functor/Contravariant.hs
--- a/Data/Functor/Contravariant.hs
+++ b/Data/Functor/Contravariant.hs
@@ -1,17 +1,21 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE TypeOperators #-}
+
+#ifdef __GLASGOW_HASKELL__
+#define LANGUAGE_DeriveDataTypeable
 {-# LANGUAGE DeriveDataTypeable #-}
-#if __GLASGOW_HASKELL__ >= 702
-#if MIN_VERSION_transformers(0,3,0)
-#if MIN_VERSION_tagged(0,6,1)
-{-# LANGUAGE Safe #-}
-#else
-{-# LANGUAGE Trustworthy #-}
 #endif
+
+#ifndef MIN_VERSION_tagged
+#define MIN_VERSION_tagged(x,y,z) 1
+#endif
+
+#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 702 && MIN_VERSION_transformers(0,3,0) && MIN_VERSION_tagged(0,6,1)
+{-# LANGUAGE Safe #-}
 #else
 {-# LANGUAGE Trustworthy #-}
 #endif
-#endif
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Functor.Contravariant
@@ -51,18 +55,30 @@
 
 import Control.Applicative
 import Control.Applicative.Backwards
+
 import Control.Category
+
 import Data.Functor.Product
+import Data.Functor.Sum
 import Data.Functor.Constant
 import Data.Functor.Compose
 import Data.Functor.Reverse
-import GHC.Generics
-import Prelude hiding ((.),id)
+
+#ifdef LANGUAGE_DeriveDataTypeable
 import Data.Typeable
-#if __GLASGOW_HASKELL__ < 707
+#endif
+
+#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ < 707 && defined(VERSION_tagged)
 import Data.Proxy
 #endif
 
+#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 702
+#define GHC_GENERICS
+import GHC.Generics
+#endif
+
+import Prelude hiding ((.),id)
+
 -- | Any instance should be subject to the following laws:
 --
 -- > contramap id = id
@@ -91,6 +107,7 @@
 (>$$<) = flip contramap
 {-# INLINE (>$$<) #-}
 
+#ifdef GHC_GENERICS
 instance Contravariant V1 where
   contramap _ x = x `seq` undefined
 
@@ -116,7 +133,12 @@
 instance (Contravariant f, Contravariant g) => Contravariant (f :+: g) where
   contramap f (L1 xs) = L1 (contramap f xs)
   contramap f (R1 ys) = R1 (contramap f ys)
+#endif
 
+instance (Contravariant f, Contravariant g) => Contravariant (Sum f g) where
+  contramap f (InL xs) = InL (contramap f xs)
+  contramap f (InR ys) = InR (contramap f ys)
+
 instance (Contravariant f, Contravariant g) => Contravariant (Product f g) where
   contramap f (Pair a b) = Pair (contramap f a) (contramap f b)
 
@@ -138,16 +160,16 @@
   contramap f = Reverse . contramap f . getReverse
   {-# INLINE contramap #-}
 
+#if (defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 707) || defined(VERSION_tagged)
 instance Contravariant Proxy where
   contramap _ Proxy = Proxy
+#endif
 
 newtype Predicate a = Predicate { getPredicate :: a -> Bool }
-#ifdef __GLASGOW_HASKELL__
+#ifdef LANGUAGE_DeriveDataTypeable
   deriving Typeable
 #endif
 
-
-
 -- | A 'Predicate' is a 'Contravariant' 'Functor', because 'contramap' can
 -- apply its function argument to the input of the predicate.
 instance Contravariant Predicate where
@@ -155,7 +177,7 @@
 
 -- | Defines a total ordering on a type as per 'compare'
 newtype Comparison a = Comparison { getComparison :: a -> a -> Ordering }
-#ifdef __GLASGOW_HASKELL__
+#ifdef LANGUAGE_DeriveDataTypeable
   deriving Typeable
 #endif
 
@@ -171,7 +193,7 @@
 
 -- | Define an equivalence relation
 newtype Equivalence a = Equivalence { getEquivalence :: a -> a -> Bool }
-#ifdef __GLASGOW_HASKELL__
+#ifdef LANGUAGE_DeriveDataTypeable
   deriving Typeable
 #endif
 
@@ -187,7 +209,7 @@
 
 -- | Dual function arrows.
 newtype Op a b = Op { getOp :: b -> a }
-#ifdef __GLASGOW_HASKELL__
+#ifdef LANGUAGE_DeriveDataTypeable
   deriving Typeable
 #endif
 
@@ -197,4 +219,3 @@
 
 instance Contravariant (Op a) where
   contramap f g = Op (getOp g . f)
-
diff --git a/Data/Functor/Contravariant/Day.hs b/Data/Functor/Contravariant/Day.hs
--- a/Data/Functor/Contravariant/Day.hs
+++ b/Data/Functor/Contravariant/Day.hs
@@ -12,7 +12,7 @@
 #endif
 -----------------------------------------------------------------------------
 -- |
--- Copyright   :  (C) 2013 Edward Kmett, Gershom Bazerman and Derek Elkins
+-- Copyright   :  (C) 2013-2014 Edward Kmett, Gershom Bazerman and Derek Elkins
 -- License     :  BSD-style (see the file LICENSE)
 --
 -- Maintainer  :  Edward Kmett <ekmett@gmail.com>
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright 2007-2011 Edward Kmett
+Copyright 2007-2014 Edward Kmett
 
 All rights reserved.
 
diff --git a/contravariant.cabal b/contravariant.cabal
--- a/contravariant.cabal
+++ b/contravariant.cabal
@@ -1,6 +1,6 @@
 name:          contravariant
 category:      Control, Data
-version:       0.5.2
+version:       0.6
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
@@ -9,7 +9,7 @@
 stability:     provisional
 homepage:      http://github.com/ekmett/contravariant/
 bug-reports:   http://github.com/ekmett/contravariant/issues
-copyright:     Copyright (C) 2007-2013 Edward A. Kmett
+copyright:     Copyright (C) 2007-2014 Edward A. Kmett
 synopsis:      Contravariant functors
 description:   Contravariant functors
 build-type:    Simple
@@ -21,13 +21,23 @@
   type: git
   location: git://github.com/ekmett/contravariant.git
 
+flag tagged
+  description:
+    You can disable the use of the `tagged` package on older versons of GHC using `-f-tagged`.
+    .
+    Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
+  default: True
+  manual: True
+
 library
   build-depends:
-    base                            < 5,
-    tagged              >= 0.4.4 && < 1,
-    transformers        >= 0.2   && < 0.5,
-    transformers-compat >= 0.3   && < 1
+    base < 5,
+    transformers >= 0.2 && < 0.5,
+    transformers-compat >= 0.3 && < 1
 
+  if flag(tagged) && !impl(ghc >= 7.7)
+    build-depends: tagged >= 0.4.4 && < 1
+
   if impl(ghc >= 7.4 && < 7.6)
     build-depends: ghc-prim
 
@@ -35,4 +45,5 @@
     Data.Functor.Contravariant
     Data.Functor.Contravariant.Compose
     Data.Functor.Contravariant.Day
+
   ghc-options: -Wall