diff --git a/Text/Earley/Generator/Internal.hs b/Text/Earley/Generator/Internal.hs
index cec9871..e256134 100644
--- a/Text/Earley/Generator/Internal.hs
+++ b/Text/Earley/Generator/Internal.hs
@@ -83,7 +83,6 @@ instance Alternative (Results t s) where
   Results sxs <|> Results sys = Results $ (<|>) <$> sxs <*> sys
 
 instance Monad (Results t s) where
-  return = pure
   Results stxs >>= f = Results $ do
     xs <- stxs
     concat <$> mapM (\(x, ts) -> fmap (\(y, ts') -> (y, ts' ++ ts)) <$> unResults (f x)) xs
@@ -93,7 +92,6 @@ instance Semigroup (Results s t a) where
 
 instance Monoid (Results s t a) where
   mempty = empty
-  mappend = (<>)
 
 -------------------------------------------------------------------------------
 -- * States and continuations
diff --git a/Text/Earley/Grammar.hs b/Text/Earley/Grammar.hs
index 7240040..4b4ae6d 100644
--- a/Text/Earley/Grammar.hs
+++ b/Text/Earley/Grammar.hs
@@ -78,7 +78,6 @@ instance Semigroup a => Semigroup (Prod r e t a) where
 -- | Lifted instance: @mempty = 'pure' 'mempty'@
 instance Monoid a => Monoid (Prod r e t a) where
   mempty  = pure mempty
-  mappend = (<>)
 
 instance Functor (Prod r e t) where
   {-# INLINE fmap #-}
@@ -161,11 +160,10 @@ instance Functor (Grammar r) where
   fmap f (Return x)      = Return $ f x
 
 instance Applicative (Grammar r) where
-  pure  = return
+  pure  = Return
   (<*>) = ap
 
 instance Monad (Grammar r) where
-  return = Return
   RuleBind ps f >>= k = RuleBind ps (f >=> k)
   FixBind f g   >>= k = FixBind f (g >=> k)
   Return x      >>= k = k x
diff --git a/Text/Earley/Parser/Internal.hs b/Text/Earley/Parser/Internal.hs
index a2b089d..cc76eae 100644
--- a/Text/Earley/Parser/Internal.hs
+++ b/Text/Earley/Parser/Internal.hs
@@ -85,7 +85,6 @@ instance Alternative (Results s) where
   Results sxs <|> Results sys = Results $ (<|>) <$> sxs <*> sys
 
 instance Monad (Results s) where
-  return = pure
   Results stxs >>= f = Results $ do
     xs <- stxs
     concat <$> mapM (unResults . f) xs
@@ -95,7 +94,6 @@ instance Semigroup (Results s a) where
 
 instance Monoid (Results s a) where
   mempty = empty
-  mappend = (<>)
 
 -------------------------------------------------------------------------------
 -- * States and continuations