diff --git a/Data/Functor/Constant.hs b/Data/Functor/Constant.hs
--- a/Data/Functor/Constant.hs
+++ b/Data/Functor/Constant.hs
@@ -34,6 +34,10 @@
 #if MIN_VERSION_base(4,8,0)
 import Data.Bifunctor (Bifunctor(..))
 #endif
+#if MIN_VERSION_base(4,10,0)
+import Data.Bifoldable (Bifoldable(..))
+import Data.Bitraversable (Bitraversable(..))
+#endif
 import Prelude hiding (null, length)
 
 -- | Constant functor.
@@ -114,4 +118,14 @@
     {-# INLINE first #-}
     second _ (Constant x) = Constant x
     {-# INLINE second #-}
+#endif
+
+#if MIN_VERSION_base(4,10,0)
+instance Bifoldable Constant where
+    bifoldMap f _ (Constant a) = f a
+    {-# INLINE bifoldMap #-}
+
+instance Bitraversable Constant where
+    bitraverse f _ (Constant a) = Constant <$> f a
+    {-# INLINE bitraverse #-}
 #endif
diff --git a/changelog b/changelog
--- a/changelog
+++ b/changelog
@@ -1,5 +1,8 @@
 -*-change-log-*-
 
+0.5.4.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017
+	* Migrate Bifoldable and Bitraversable instances for Constant
+
 0.5.3.1 Ross Paterson <R.Paterson@city.ac.uk> Feb 2017
 	* Fixed for pre-AMP environments
 
diff --git a/transformers.cabal b/transformers.cabal
--- a/transformers.cabal
+++ b/transformers.cabal
@@ -1,5 +1,5 @@
 name:         transformers
-version:      0.5.3.1
+version:      0.5.4.0
 license:      BSD3
 license-file: LICENSE
 author:       Andy Gill, Ross Paterson