diff --git a/either.cabal b/either.cabal
--- a/either.cabal
+++ b/either.cabal
@@ -1,6 +1,6 @@
 name:          either
 category:      Control, Monads
-version:       4.1
+version:       4.1.1
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
diff --git a/src/Control/Monad/Trans/Either.hs b/src/Control/Monad/Trans/Either.hs
--- a/src/Control/Monad/Trans/Either.hs
+++ b/src/Control/Monad/Trans/Either.hs
@@ -62,7 +62,7 @@
 -- apomorphism is the generalized anamorphism for this Monad, but it cannot be
 -- written with 'ErrorT'.
 --
--- In addition to the combinators here, the @errors@ package provides a large 
+-- In addition to the combinators here, the @errors@ package provides a large
 -- number of combinators for working with this type.
 newtype EitherT e m a = EitherT { runEitherT :: m (Either e a) }
 
@@ -269,18 +269,18 @@
     EitherT <$> traverse (either (pure . Left) (fmap Right . f)) a
   {-# INLINE traverse #-}
 
-instance (Error e, MonadBase b m) => MonadBase b (EitherT e m) where
+instance MonadBase b m => MonadBase b (EitherT e m) where
   liftBase = liftBaseDefault
   {-# INLINE liftBase #-}
 
-instance Error e => MonadTransControl (EitherT e) where
+instance MonadTransControl (EitherT e) where
   newtype StT (EitherT e) a = StEitherT {unStEitherT :: Either e a}
   liftWith f = EitherT $ liftM return $ f $ liftM StEitherT . runEitherT
   {-# INLINE liftWith #-}
   restoreT = EitherT . liftM unStEitherT
   {-# INLINE restoreT #-}
 
-instance (Error e, MonadBaseControl b m) => MonadBaseControl b (EitherT e m) where
+instance MonadBaseControl b m => MonadBaseControl b (EitherT e m) where
   newtype StM (EitherT e m) a = StMEitherT { unStMEitherT :: StM m (StT (EitherT e) a) }
   liftBaseWith = defaultLiftBaseWith StMEitherT
   {-# INLINE liftBaseWith #-}
diff --git a/src/Data/Either/Combinators.hs b/src/Data/Either/Combinators.hs
--- a/src/Data/Either/Combinators.hs
+++ b/src/Data/Either/Combinators.hs
@@ -39,7 +39,7 @@
 -- ---------------------------------------------------------------------------
 -- Functions over Either
 
--- |The 'isLeft' function returns 'True' iff its argument is of the form @Left _@.
+-- |The 'isLeft' function returns 'True' iff its argument is of the form @'Left' _@.
 --
 -- Using @Control.Lens@:
 --
@@ -56,7 +56,7 @@
 isLeft (Left _) = True
 isLeft _        = False
 
--- |The 'isRight' function returns 'True' iff its argument is of the form @Right _@.
+-- |The 'isRight' function returns 'True' iff its argument is of the form @'Right' _@.
 --
 -- Using @Control.Lens@:
 --
@@ -89,7 +89,7 @@
 fromLeft' (Left x)  = x
 
 -- | Extracts the element out of a 'Right' and
--- throws an error if its argument take the form  @'Left' _@.
+-- throws an error if its argument take the form @'Left' _@.
 --
 -- Using @Control.Lens@:
 --
@@ -128,7 +128,7 @@
 mapBoth _ f (Right x) = Right (f x)
 
 -- | The 'mapLeft' function takes a function and applies it to an Either value
--- iff the value takes the form 'Left _'.
+-- iff the value takes the form @'Left' _@.
 --
 -- Using @Data.Bifunctor@:
 --
@@ -156,13 +156,13 @@
 mapLeft :: (a -> c) -> Either a b -> Either c b
 mapLeft f = mapBoth f id
 
--- | The 'mapLeft' function takes a function and applies it to an Either value
--- iff the value takes the form 'Left _'.
+-- | The 'mapRight' function takes a function and applies it to an Either value
+-- iff the value takes the form @'Right' _@.
 --
 -- Using @Data.Bifunctor@:
 --
 -- @
--- 'mapRight' = first
+-- 'mapRight' = second
 -- @
 --
 -- Using @Control.Arrow@:
@@ -174,7 +174,7 @@
 -- Using @Control.Lens@:
 --
 -- @
--- 'mapRight' = 'over' '_Right'
+-- 'mapRight' = over _Right
 -- @
 --
 -- >>> mapRight (*2) (Left "hello")
@@ -186,7 +186,7 @@
 mapRight = mapBoth id
 
 -- | The 'whenLeft' function takes an 'Either' value and a function which returns a monad.
--- The monad is only executed when the given argument takes the form @Left _@, otherwise
+-- The monad is only executed when the given argument takes the form @'Left' _@, otherwise
 -- it does nothing.
 --
 -- Using @Control.Lens@:
@@ -201,8 +201,8 @@
 whenLeft (Left x) f = f x
 whenLeft _        _ = pure ()
 
--- | The 'whenLeft' function takes an 'Either' value and a function which returns a monad.
--- The monad is only executed when the given argument takes the form @Right _@, otherwise
+-- | The 'whenRight' function takes an 'Either' value and a function which returns a monad.
+-- The monad is only executed when the given argument takes the form @'Right' _@, otherwise
 -- it does nothing.
 --
 -- Using @Data.Foldable@: