diff --git a/.travis.yml b/.travis.yml
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,12 +9,6 @@
       - "\x0313bifunctors\x03/\x0306%{branch}\x03 \x0314%{commit}\x03 %{build_url} %{message}"
 
 env:
- # - GHCVER=7.0.1
- # - GHCVER=7.0.2
- # - GHCVER=7.0.3
- # - GHCVER=7.0.4
- # - GHCVER=7.2.1
- # - GHCVER=7.2.2
  - GHCVER=7.4.1
  - GHCVER=7.4.2
  - GHCVER=7.6.1
@@ -41,7 +35,7 @@
 script:
  - cabal-1.18 configure --enable-tests -v2
  - cabal-1.18 build --ghc-options=-ddump-minimal-imports
- - packunused
+ # - packunused
  - packdeps bifunctors.cabal
  - cabal-1.18 test
  - cabal-1.18 check
diff --git a/bifunctors.cabal b/bifunctors.cabal
--- a/bifunctors.cabal
+++ b/bifunctors.cabal
@@ -1,6 +1,6 @@
 name:          bifunctors
 category:      Data, Functors
-version:       4.2
+version:       4.2.1
 license:       BSD3
 cabal-version: >= 1.6
 license-file:  LICENSE
@@ -23,8 +23,9 @@
   hs-source-dirs: src
   build-depends:
     base          >= 4.5 && < 5,
-    semigroups    >= 0.8.3.1,
+    semigroups    >= 0.8.3.1 && < 1,
     semigroupoids == 4.*,
+
     tagged        >= 0.7.3 && < 1
 
   if impl(ghc<7.9)
diff --git a/old-src/Data/Bifunctor.hs b/old-src/Data/Bifunctor.hs
--- a/old-src/Data/Bifunctor.hs
+++ b/old-src/Data/Bifunctor.hs
@@ -16,6 +16,7 @@
 
 import Control.Applicative
 import Data.Tagged
+import Data.Semigroup
 
 -- | Minimal definition either 'bimap' or 'first' and 'second'
 
@@ -78,6 +79,11 @@
 instance Bifunctor (,) where
   bimap f g ~(a, b) = (f a, g b)
   {-# INLINE bimap #-}
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Bifunctor Arg where
+  bimap f g (Arg a b) = Arg (f a) (g b)
+#endif
 
 instance Bifunctor ((,,) x) where
   bimap f g ~(x, a, b) = (x, f a, g b)
diff --git a/src/Data/Biapplicative.hs b/src/Data/Biapplicative.hs
--- a/src/Data/Biapplicative.hs
+++ b/src/Data/Biapplicative.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Bifunctor.Apply
@@ -22,7 +23,7 @@
 import Control.Applicative
 import Data.Bifunctor
 import Data.Bifunctor.Apply ((<<$>>))
-import Data.Monoid
+import Data.Semigroup
 import Data.Tagged
 
 infixl 4 <<*>>, <<*, *>>, <<**>>
@@ -67,6 +68,14 @@
   {-# INLINE bipure #-}
   (f, g) <<*>> (a, b) = (f a, g b)
   {-# INLINE (<<*>>) #-}
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Biapplicative Arg where
+  bipure = Arg
+  {-# INLINE bipure #-}
+  Arg f g <<*>> Arg a b = Arg (f a) (g b)
+  {-# INLINE (<<*>>) #-}
+#endif
 
 instance Monoid x => Biapplicative ((,,) x) where
   bipure = (,,) mempty
diff --git a/src/Data/Bifoldable.hs b/src/Data/Bifoldable.hs
--- a/src/Data/Bifoldable.hs
+++ b/src/Data/Bifoldable.hs
@@ -30,7 +30,7 @@
   ) where
 
 import Control.Applicative
-import Data.Monoid
+import Data.Semigroup
 import Data.Tagged
 
 -- | Minimal definition either 'bifoldr' or 'bifoldMap'
@@ -89,6 +89,11 @@
 
 #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708
   {-# MINIMAL bifoldr | bifoldMap #-}
+#endif
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Bifoldable Arg where
+  bifoldMap f g (Arg a b) = f a `mappend` g b
 #endif
 
 instance Bifoldable (,) where
diff --git a/src/Data/Bifunctor/Apply.hs b/src/Data/Bifunctor/Apply.hs
--- a/src/Data/Bifunctor/Apply.hs
+++ b/src/Data/Bifunctor/Apply.hs
@@ -1,7 +1,8 @@
+{-# LANGUAGE CPP #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Bifunctor.Apply
--- Copyright   :  (C) 2011 Edward Kmett,
+-- Copyright   :  (C) 2011-2015 Edward Kmett,
 -- License     :  BSD-style (see the file LICENSE)
 --
 -- Maintainer  :  Edward Kmett <ekmett@gmail.com>
@@ -66,6 +67,12 @@
 instance Biapply (,) where
   (f, g) <<.>> (a, b) = (f a, g b)
   {-# INLINE (<<.>>) #-}
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Biapply Arg where
+  Arg f g <<.>> Arg a b = Arg (f a) (g b)
+  {-# INLINE (<<.>>) #-}
+#endif
 
 instance Semigroup x => Biapply ((,,) x) where
   (x, f, g) <<.>> (x', a, b) = (x <> x', f a, g b)
diff --git a/src/Data/Bifunctor/Flip.hs b/src/Data/Bifunctor/Flip.hs
--- a/src/Data/Bifunctor/Flip.hs
+++ b/src/Data/Bifunctor/Flip.hs
@@ -24,7 +24,7 @@
 import Data.Semigroup.Bitraversable
 import Data.Traversable
 
--- | Make a 'Functor' over the first argument of a 'Bifunctor'.
+-- | Make a 'Bifunctor' flipping the arguments of a 'Bifunctor'.
 newtype Flip p a b = Flip { runFlip :: p b a }
   deriving (Eq,Ord,Show,Read)
 
diff --git a/src/Data/Bitraversable.hs b/src/Data/Bitraversable.hs
--- a/src/Data/Bitraversable.hs
+++ b/src/Data/Bitraversable.hs
@@ -23,7 +23,7 @@
 import Control.Applicative
 import Data.Bifunctor
 import Data.Bifoldable
-import Data.Monoid
+import Data.Semigroup
 import Data.Tagged
 
 -- | Minimal complete definition either 'bitraverse' or 'bisequenceA'.
@@ -149,6 +149,11 @@
 
 #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708
   {-# MINIMAL bitraverse | bisequenceA #-}
+#endif
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Bitraversable Arg where
+  bitraverse f g (Arg a b) = Arg <$> f a <*> g b
 #endif
 
 instance Bitraversable (,) where
diff --git a/src/Data/Semigroup/Bifoldable.hs b/src/Data/Semigroup/Bifoldable.hs
--- a/src/Data/Semigroup/Bifoldable.hs
+++ b/src/Data/Semigroup/Bifoldable.hs
@@ -1,7 +1,8 @@
+{-# LANGUAGE CPP #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Semigroup.Foldable
--- Copyright   :  (C) 2011 Edward Kmett
+-- Copyright   :  (C) 2011-2015 Edward Kmett
 -- License     :  BSD-style (see the file LICENSE)
 --
 -- Maintainer  :  Edward Kmett <ekmett@gmail.com>
@@ -32,6 +33,11 @@
   bifoldMap1 :: Semigroup m => (a -> m) -> (b -> m) -> t a b -> m
   bifoldMap1 f g = maybe (error "bifoldMap1") id . getOption . bifoldMap (Option . Just . f) (Option . Just . g)
   {-# INLINE bifoldMap1 #-}
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Bifoldable1 Arg where
+  bifoldMap1 f g (Arg a b) = f a <> g b
+#endif
 
 instance Bifoldable1 Either where
   bifoldMap1 f _ (Left a) = f a
diff --git a/src/Data/Semigroup/Bitraversable.hs b/src/Data/Semigroup/Bitraversable.hs
--- a/src/Data/Semigroup/Bitraversable.hs
+++ b/src/Data/Semigroup/Bitraversable.hs
@@ -2,7 +2,7 @@
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Semigroup.Bitraversable
--- Copyright   :  (C) 2011 Edward Kmett
+-- Copyright   :  (C) 2011-2015 Edward Kmett
 -- License     :  BSD-style (see the file LICENSE)
 --
 -- Maintainer  :  Edward Kmett <ekmett@gmail.com>
@@ -34,6 +34,11 @@
 
 #if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 708
   {-# MINIMAL bitraverse1 | bisequence1 #-}
+#endif
+
+#if MIN_VERSION_semigroups(0,16,2)
+instance Bitraversable1 Arg where
+  bitraverse1 f g (Arg a b) = Arg <$> f a <.> g b
 #endif
 
 bifoldMap1Default :: (Bitraversable1 t, Semigroup m) => (a -> m) -> (b -> m) -> t a b -> m