diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,7 @@
+4.2
+---
+* `contravariant` 1.0 support. `Day` convolution moves to `kan-extensions`.
+
 4.0.3
 -----
 * Silenced `Control.Monad.Instances` deprecation warnings on GHC 7.8
diff --git a/adjunctions.cabal b/adjunctions.cabal
--- a/adjunctions.cabal
+++ b/adjunctions.cabal
@@ -1,6 +1,6 @@
 name:          adjunctions
 category:      Data Structures, Adjunctions
-version:       4.1.0.1
+version:       4.2
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
@@ -44,7 +44,7 @@
     base          >= 4       && < 5,
     comonad       >= 4       && < 5,
     containers    >= 0.3     && < 0.6,
-    contravariant >= 0.4.1   && < 1,
+    contravariant >= 1       && < 2,
     distributive  >= 0.4     && < 1,
     free          >= 4       && < 5,
     mtl           >= 2.0.1   && < 2.3,
diff --git a/src/Data/Functor/Contravariant/Rep.hs b/src/Data/Functor/Contravariant/Rep.hs
--- a/src/Data/Functor/Contravariant/Rep.hs
+++ b/src/Data/Functor/Contravariant/Rep.hs
@@ -23,7 +23,6 @@
 
 import Control.Monad.Reader
 import Data.Functor.Contravariant
-import Data.Functor.Contravariant.Day
 import Data.Functor.Product
 import Data.Profunctor
 import Data.Proxy
@@ -73,17 +72,6 @@
   tabulate _ = Proxy
   index Proxy _ = ()
   contramapWithRep _ Proxy = Proxy
-
-instance (Representable f, Representable g) => Representable (Day f g) where
-  type Rep (Day f g) = (Rep f, Rep g)
-  tabulate a2fg = Day (tabulate fst) (tabulate snd) $ \a -> let b = a2fg a in (b,b)
-  index (Day fb gc abc) a = case abc a of
-    (b, c) -> (index fb b, index gc c)
-  contramapWithRep d2eafg (Day fb gc abc) = Day (contramapWithRep id fb) (contramapWithRep id gc) $ \d -> case d2eafg d of
-    Left a -> case abc a of
-      (b, c) -> (Left b, Left c)
-    Right (vf, vg) -> (Right vf, Right vg)
-  {-# INLINE tabulate #-}
 
 instance Representable (Op r) where
   type Rep (Op r) = r