diff --git a/Control/Concurrent/Async/Internal.hs b/Control/Concurrent/Async/Internal.hs
index fe65c90..9ad660f 100644
--- a/Control/Concurrent/Async/Internal.hs
+++ b/Control/Concurrent/Async/Internal.hs
@@ -57,6 +57,10 @@ import GHC.Exts
 import GHC.IO hiding (finally, onException)
 import GHC.Conc (ThreadId(..))
 
+#if defined(__MHS__)
+import Data.Traversable
+#endif
+
 #ifdef DEBUG_AUTO_LABEL
 import qualified GHC.Stack
 #endif
diff --git a/Control/Concurrent/Async/Warden.hs b/Control/Concurrent/Async/Warden.hs
index ec259be..a3b19a5 100644
--- a/Control/Concurrent/Async/Warden.hs
+++ b/Control/Concurrent/Async/Warden.hs
@@ -5,7 +5,7 @@
   This source code is licensed under the BSD-style license found in the
   LICENSE file in the root directory of this source tree.
 -}
-
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 
@@ -27,11 +27,17 @@ import Control.Concurrent.Async (Async)
 import qualified Control.Concurrent.Async as Async
 import Control.Concurrent.MVar
 import Control.Exception
-import Control.Monad
 import Data.HashSet (HashSet)
 import qualified Data.HashSet as HashSet
 import System.IO (fixIO)
 
+#if defined(__MHS__)
+import Prelude hiding(mapM_)
+import Control.Monad hiding(mapM_)
+import Data.Foldable(mapM_)
+#else
+import Control.Monad
+#endif
 
 -- | A 'Warden' is an owner of 'Async's which cancels them on 'shutdown'.
 --