diff --git a/CHANGELOG.markdown b/CHANGELOG.markdown
--- a/CHANGELOG.markdown
+++ b/CHANGELOG.markdown
@@ -1,3 +1,8 @@
+4.1.1
+----
+* Generalized the types of `mapping`, `bimapping`, `contramapping`, `dimapping`, `lmapping`, `rmapping` to support changing the `Functor`, `Bifunctor`, `Contravariant`, and `Profunctor` respectively.
+* Compatibility with `free` 4.6
+
 4.1
 ---
 * Added `Plated` instances for various free monad variants.
diff --git a/lens.cabal b/lens.cabal
--- a/lens.cabal
+++ b/lens.cabal
@@ -1,6 +1,6 @@
 name:          lens
 category:      Data, Lenses, Generics
-version:       4.1
+version:       4.1.1
 license:       BSD3
 cabal-version: >= 1.8
 license-file:  LICENSE
@@ -304,6 +304,8 @@
 
   other-modules:
     Control.Lens.Internal.TupleIxedTH
+
+  cpp-options: -traditional
 
   if flag(safe)
     cpp-options: -DSAFE=1
diff --git a/src/Control/Lens/Combinators.hs b/src/Control/Lens/Combinators.hs
--- a/src/Control/Lens/Combinators.hs
+++ b/src/Control/Lens/Combinators.hs
@@ -1,4 +1,3 @@
-
 --------------------------------------------------------------------------------
 -- |
 -- Module      :  Control.Lens.Combinators
diff --git a/src/Control/Lens/Equality.hs b/src/Control/Lens/Equality.hs
--- a/src/Control/Lens/Equality.hs
+++ b/src/Control/Lens/Equality.hs
@@ -22,6 +22,8 @@
   , mapEq
   , fromEq
   , simply
+  -- * The Trivial Equality
+  , simple
   -- * Implementation Details
   , Identical(..)
   ) where
@@ -77,3 +79,11 @@
 simply :: (Optic' p f s a -> r) -> Optic' p f s a -> r
 simply = id
 {-# INLINE simply #-}
+
+-- | Composition with this isomorphism is occasionally useful when your 'Lens',
+-- 'Control.Lens.Traversal.Traversal' or 'Iso' has a constraint on an unused
+-- argument to force that argument to agree with the
+-- type of a used argument and avoid @ScopedTypeVariables@ or other ugliness.
+simple :: Equality' a a
+simple = id
+{-# INLINE simple #-}
diff --git a/src/Control/Lens/Iso.hs b/src/Control/Lens/Iso.hs
--- a/src/Control/Lens/Iso.hs
+++ b/src/Control/Lens/Iso.hs
@@ -62,6 +62,7 @@
   , bimapping
   ) where
 
+import Control.Lens.Equality (simple)
 import Control.Lens.Fold
 import Control.Lens.Internal.Context
 import Control.Lens.Internal.Indexed
@@ -215,18 +216,10 @@
 {-# INLINE enum #-}
 
 -- | This can be used to lift any 'Iso' into an arbitrary 'Functor'.
-mapping :: Functor f => AnIso s t a b -> Iso (f s) (f t) (f a) (f b)
+mapping :: (Functor f, Functor g) => AnIso s t a b -> Iso (f s) (g t) (f a) (g b)
 mapping k = withIso k $ \ sa bt -> iso (fmap sa) (fmap bt)
 {-# INLINE mapping #-}
 
--- | Composition with this isomorphism is occasionally useful when your 'Lens',
--- 'Control.Lens.Traversal.Traversal' or 'Iso' has a constraint on an unused
--- argument to force that argument to agree with the
--- type of a used argument and avoid @ScopedTypeVariables@ or other ugliness.
-simple :: Iso' a a
-simple = id
-{-# INLINE simple #-}
-
 -- | If @v@ is an element of a type @a@, and @a'@ is @a@ sans the element @v@, then @'non' v@ is an isomorphism from
 -- @'Maybe' a'@ to @a@.
 --
@@ -464,7 +457,7 @@
 -- dimapping :: 'Profunctor' p => 'Iso' s t a b -> 'Iso' s' t' a' b' -> 'Iso' (p a s') (p b t') (p s a') (p t b')
 -- dimapping :: 'Profunctor' p => 'Iso'' s a -> 'Iso'' s' a' -> 'Iso'' (p a s') (p s a')
 -- @
-dimapping :: Profunctor p => AnIso s t a b -> AnIso s' t' a' b' -> Iso (p a s') (p b t') (p s a') (p t b')
+dimapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> AnIso s' t' a' b' -> Iso (p a s') (q b t') (p s a') (q t b')
 dimapping f g = withIso f $ \ sa bt -> withIso g $ \ s'a' b't' ->
   iso (dimap sa s'a') (dimap bt b't')
 {-# INLINE dimapping #-}
@@ -475,7 +468,7 @@
 -- lmapping :: 'Profunctor' p => 'Iso' s t a b -> 'Iso' (p a x) (p b y) (p s x) (p t y)
 -- lmapping :: 'Profunctor' p => 'Iso'' s a -> 'Iso'' (p a x) (p s x)
 -- @
-lmapping :: Profunctor p => AnIso s t a b -> Iso (p a x) (p b y) (p s x) (p t y)
+lmapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> Iso (p a x) (q b y) (p s x) (q t y)
 lmapping f = withIso f $ \ sa bt -> iso (lmap sa) (lmap bt)
 {-# INLINE lmapping #-}
 
@@ -485,7 +478,7 @@
 -- rmapping :: 'Profunctor' p => 'Iso' s t a b -> 'Iso' (p x s) (p y t) (p x a) (p y b)
 -- rmapping :: 'Profunctor' p => 'Iso'' s a -> 'Iso'' (p x s) (p x a)
 -- @
-rmapping :: Profunctor p => AnIso s t a b -> Iso (p x s) (p y t) (p x a) (p y b)
+rmapping :: (Profunctor p, Profunctor q) => AnIso s t a b -> Iso (p x s) (q y t) (p x a) (q y b)
 rmapping g = withIso g $ \ sa bt -> iso (rmap sa) (rmap bt)
 {-# INLINE rmapping #-}
 
@@ -499,7 +492,7 @@
 -- bimapping :: 'Profunctor' p => 'Iso' s t a b -> 'Iso' s' t' a' b' -> 'Iso' (p s s') (p t t') (p a a') (p b b')
 -- bimapping :: 'Profunctor' p => 'Iso'' s a -> 'Iso'' s' a' -> 'Iso'' (p s s') (p a a')
 -- @
-bimapping :: Bifunctor f => AnIso s t a b -> AnIso s' t' a' b' -> Iso (f s s') (f t t') (f a a') (f b b')
+bimapping :: (Bifunctor f, Bifunctor g) => AnIso s t a b -> AnIso s' t' a' b' -> Iso (f s s') (g t t') (f a a') (g b b')
 bimapping f g = withIso f $ \ sa bt -> withIso g $ \s'a' b't' ->
   iso (bimap sa s'a') (bimap bt b't')
 {-# INLINE bimapping #-}
diff --git a/src/Control/Lens/Plated.hs b/src/Control/Lens/Plated.hs
--- a/src/Control/Lens/Plated.hs
+++ b/src/Control/Lens/Plated.hs
@@ -12,6 +12,10 @@
 #ifndef MIN_VERSION_template_haskell
 #define MIN_VERSION_template_haskell(x,y,z) 1
 #endif
+
+#ifndef MIN_VERSION_free
+#define MIN_VERSION_free(x,y,z) 1
+#endif
 -------------------------------------------------------------------------------
 -- |
 -- Module      :  Control.Lens.Plated
@@ -91,8 +95,9 @@
 import Control.Monad.Free as Monad
 import Control.Monad.Free.Church as Church
 import Control.Monad.Trans.Free as Trans
--- import Control.Monad.Trans.Free.Church as ChurchT
+#if !(MIN_VERSION_free(4,6,0))
 import Control.MonadPlus.Free as MonadPlus
+#endif
 import qualified Language.Haskell.TH as TH
 import Data.Aeson
 import Data.Bitraversable
@@ -216,10 +221,12 @@
 instance (Traversable f, Traversable m) => Plated (Trans.FreeT f m a) where
   plate f (Trans.FreeT xs) = Trans.FreeT <$> traverse (bitraverse pure f) xs
 
+#if !(MIN_VERSION_free(4,6,0))
 instance Traversable f => Plated (MonadPlus.Free f a) where
   plate f (MonadPlus.Free as) = MonadPlus.Free <$> traverse f as
   plate f (MonadPlus.Plus as) = MonadPlus.Plus <$> traverse f as
   plate _ x         = pure x
+#endif
 
 instance Traversable f => Plated (Church.F f a) where
   plate f = fmap Church.toF . plate (fmap Church.fromF . f . Church.toF) . Church.fromF