diff --git a/pipes-concurrency.cabal b/pipes-concurrency.cabal
--- a/pipes-concurrency.cabal
+++ b/pipes-concurrency.cabal
@@ -1,5 +1,5 @@
 Name: pipes-concurrency
-Version: 2.0.9
+Version: 2.0.10
 Cabal-Version: >=1.8.0.2
 Build-Type: Simple
 License: BSD3
@@ -31,16 +31,17 @@
 Library
     Hs-Source-Dirs: src
     Build-Depends:
-        base          >= 4       && < 5  ,
-        async         >= 2.0.0.0 && < 2.3,
-        contravariant >= 1.3.3   && < 1.5,
-        pipes         >= 4.0     && < 4.4,
-        stm           >= 2.4.3   && < 2.5,
+        base          >= 4       && < 5   ,
+        async         >= 2.0.0.0 && < 2.3 ,
+        contravariant >= 1.3.3   && < 1.5 ,
+        pipes         >= 4.0     && < 4.4 ,
+        semigroups                  < 0.19,
+        stm           >= 2.4.3   && < 2.5 ,
         void          >= 0.6     && < 1
     Exposed-Modules:
         Pipes.Concurrent,
         Pipes.Concurrent.Tutorial
-    GHC-Options: -O2
+    GHC-Options: -O2 -Wall -Wcompat
 
 Test-Suite tests
     Type: exitcode-stdio-1.0
diff --git a/src/Pipes/Concurrent.hs b/src/Pipes/Concurrent.hs
--- a/src/Pipes/Concurrent.hs
+++ b/src/Pipes/Concurrent.hs
@@ -1,6 +1,6 @@
 -- | Asynchronous communication between pipes
 
-{-# LANGUAGE RankNTypes, Safe #-}
+{-# LANGUAGE CPP, RankNTypes, Safe #-}
 
 module Pipes.Concurrent (
     -- * Inputs and Outputs
@@ -39,8 +39,10 @@
 import Data.Functor.Contravariant.Divisible (
     Divisible(divide, conquer), Decidable(lose, choose))
 import Data.Monoid (Monoid(mempty, mappend))
+import Data.Semigroup
 import Data.Void (absurd)
 import Pipes (MonadIO(liftIO), yield, await, Producer', Consumer')
+import Prelude hiding (read)
 import System.Mem (performGC)
 
 import qualified Control.Concurrent.Async
@@ -81,10 +83,16 @@
     mzero = empty
     mplus = (<|>)
 
+instance Data.Semigroup.Semigroup (Input a) where
+    (<>) = (<|>)
+
 instance Monoid (Input a) where
     mempty = empty
-    mappend = (<|>)
 
+#if !(MIN_VERSION_base(4,11,0))
+    mappend = (<>)
+#endif
+
 {-| An exhaustible sink of values
 
     'send' returns 'False' if the sink is exhausted
@@ -92,9 +100,15 @@
 newtype Output a = Output {
     send :: a -> S.STM Bool }
 
+instance Data.Semigroup.Semigroup (Output a) where
+    i1 <> i2 = Output (\a -> (||) <$> send i1 a <*> send i2 a)
+
 instance Monoid (Output a) where
     mempty  = Output (\_ -> return False)
-    mappend i1 i2 = Output (\a -> (||) <$> send i1 a <*> send i2 a)
+
+#if !(MIN_VERSION_base(4,11,0))
+    mappend = (<>)
+#endif
 
 -- | This instance is useful for creating new tagged address, similar to elm's
 -- Signal.forwardTo. In fact elm's forwardTo is just 'flip contramap'