diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# 1.10.4
+* Backported `MonadPlus` and `MonadZip` instances for `U1`, and made the
+  `Functor`, `Foldable`, `Traversable`, `Alternative`, and `Monad` instances
+  for `U1` lazier to correspond with `base-4.9`
+
 # 1.10.3
 * Backported `Enum`, `Bounded`, `Ix`, `Functor`, `Applicative`, `Monad`,
  `MonadFix`, `MonadPlus`, `MonadZip`, `Foldable`, `Traversable`, and
diff --git a/generic-deriving.cabal b/generic-deriving.cabal
--- a/generic-deriving.cabal
+++ b/generic-deriving.cabal
@@ -1,5 +1,5 @@
 name:                   generic-deriving
-version:                1.10.3
+version:                1.10.4
 synopsis:               Generic programming library for generalised deriving.
 description:
 
diff --git a/src/Generics/Deriving/Base/Internal.hs b/src/Generics/Deriving/Base/Internal.hs
--- a/src/Generics/Deriving/Base/Internal.hs
+++ b/src/Generics/Deriving/Base/Internal.hs
@@ -669,18 +669,48 @@
 
 -- | Unit: used for constructors without arguments
 data U1 p = U1
-  deriving (Eq, Ord, Read, Show, Functor, Foldable, Traversable, Data, Typeable)
+  deriving (Eq, Ord, Read, Show, Data, Typeable)
+
+instance Functor U1 where
+  fmap _ _ = U1
+
 instance Applicative U1 where
   pure _ = U1
-  U1 <*> U1 = U1
+  _ <*> _ = U1
 
 instance Alternative U1 where
   empty = U1
-  U1 <|> U1 = U1
+  _ <|> _ = U1
 
 instance Monad U1 where
   return _ = U1
-  U1 >>= _ = U1
+  _ >>= _ = U1
+
+instance MonadPlus U1 where
+  mzero = U1
+  mplus _ _ = U1
+
+instance Foldable U1 where
+  foldMap _ _ = mempty
+  {-# INLINE foldMap #-}
+  fold _ = mempty
+  {-# INLINE fold #-}
+  foldr _ z _ = z
+  {-# INLINE foldr #-}
+  foldl _ z _ = z
+  {-# INLINE foldl #-}
+  foldl1 _ _ = error "foldl1: U1"
+  foldr1 _ _ = error "foldr1: U1"
+
+instance Traversable U1 where
+  traverse _ _ = pure U1
+  {-# INLINE traverse #-}
+  sequenceA _ = pure U1
+  {-# INLINE sequenceA #-}
+  mapM _ _ = return U1
+  {-# INLINE mapM #-}
+  sequence _ = return U1
+  {-# INLINE sequence #-}
 
 -- | Used for marking occurrences of the parameter
 newtype Par1 p = Par1 { unPar1 :: p }