diff --git a/Control/Async.hs b/Control/Async.hs
--- a/Control/Async.hs
+++ b/Control/Async.hs
@@ -1,23 +1,21 @@
 {- |
-   Module      :  Control.Arrow.SP
-   Copyright   :  (c) 2010 Peter Simons
+   Module      :  Control.Async
    License     :  BSD3
-
    Maintainer  :  simons@cryp.to
    Stability   :  stable
    Portability :  portable
+
+   An implementation of IO computations that return their value asynchronously.
 -}
 
 module Control.Async
-  (
-        Async                   -- Async a = Child ThreadId (AsyncMVar a)
-  ,     forkAsync               -- :: IO a -> IO (Async a)
-  ,     throwToAsync            -- :: Async a -> SomeException -> IO ()
-  ,     killAsync               -- :: Async a -> IO ()
-  ,     isReadyAsync            -- :: Async a -> IO Bool
-  ,     waitForAsync            -- :: Async a -> IO a
-
-  ,     parIO                   -- :: IO a -> IO a -> IO a
+  ( Async
+  , forkAsync
+  , throwToAsync
+  , killAsync
+  , isReadyAsync
+  , waitForAsync
+  , parIO
   )
   where
 
@@ -26,40 +24,48 @@
 
 type AsyncMVar a = MVar (Either SomeException a)
 
+-- | @Async a@ represents a value @a@ that is being computed
+-- asynchronously, i.e. a value that is going to become available at
+-- some point in the future.
 data Async a = Child ThreadId (AsyncMVar a)
 
 forkAsync' :: IO a -> AsyncMVar a -> IO (Async a)
-forkAsync' f mv = fmap (\p -> Child p mv) (block (forkIO f'))
-  where
-    f' = try (unblock f) >>= tryPutMVar mv >> return ()
+forkAsync' f mv = fmap (`Child` mv) (mask $ \unmask -> forkIO (try (unmask f) >>= tryPutMVar mv >> return ()))
 
+-- | Start an asynchronous computation.
 forkAsync :: IO a -> IO (Async a)
 forkAsync f = newEmptyMVar >>= forkAsync' f
 
-throwToAsync :: Async a -> SomeException -> IO ()
+-- | Throw an asynchronous exception to the thread that performs the
+-- computation associated with this value.
+throwToAsync :: Exception e => Async a -> e -> IO ()
 throwToAsync (Child pid _) = throwTo pid
 
+-- | Abort the asynchronous computation associated with this value.
 killAsync :: Async a -> IO ()
 killAsync (Child pid _) = killThread pid
 
+-- | Test whether the asynchronous value has become available.
 isReadyAsync :: Async a -> IO Bool
 isReadyAsync (Child _ mv) = fmap not (isEmptyMVar mv)
 
+-- | Wait for the asynchronous value to become available, and retrieve
+-- it. If the computation that generated the value has thrown an
+-- exception, then that exception will be raised here.
 waitForAsync :: Async a -> IO a
 waitForAsync (Child _ sync) = fmap (either throw id) (readMVar sync)
 
--- Run both computations in parallel and return the @a@ value
--- of the computation that terminates first. An exception in
--- either of the two computations aborts the entire parIO
--- computation.
+-- | Run both computations in parallel and return the @a@ value of the
+-- computation that terminates first. An exception in either of the two
+-- computations aborts the entire @parIO@ computation.
 
 parIO :: IO a -> IO a -> IO a
 parIO f g = do
   sync <- newEmptyMVar
   bracket
     (forkAsync' f sync)
-    (killAsync)
+    killAsync
     (\_ -> bracket
              (forkAsync' g sync)
-             (killAsync)
-             (waitForAsync))
+             killAsync
+             waitForAsync)
diff --git a/async.cabal b/async.cabal
--- a/async.cabal
+++ b/async.cabal
@@ -1,19 +1,19 @@
 Name:                   async
-Version:                1.2
-Copyright:              (c) 2004-2010 Peter Simons
+Version:                1.3
+Copyright:              (c) 2004-2011 Peter Simons
 License:                BSD3
-License-File:		LICENSE
+License-File:           LICENSE
 Author:                 Peter Simons <simons@cryp.to>
 Maintainer:             Peter Simons <simons@cryp.to>
 Homepage:               http://gitorious.org/async/
-Category:               Control
+Category:               Control, Concurrency, Parallelism
 Synopsis:               Asynchronous Computations
-
-Description:		An implementation of IO computations that return their
-			value asynchronously.
 Cabal-Version:          >= 1.6
 Build-Type:             Simple
-Tested-With:            GHC == 6.12.1
+Tested-With:            GHC == 6.12.3, GHC == 7.0.4, GHC == 7.2.1
+Description:
+  An implementation of IO computations that return their value
+  asynchronously.
 
 Source-Repository head
   Type:                 git