diff --git a/hack-handler-epoll.cabal b/hack-handler-epoll.cabal
--- a/hack-handler-epoll.cabal
+++ b/hack-handler-epoll.cabal
@@ -1,5 +1,5 @@
 name:               hack-handler-epoll
-version:            0.1.1
+version:            0.1.2
 synopsis:           hack handler implementation using epoll
 description:        Hack handler implemented using System.Linux.Epoll
 category:           Web
@@ -20,13 +20,13 @@
   ghc-options:      -Wall -O2
   build-depends:    base >= 3 && < 5,
                     unix,
-                    hack >= 2009.10.30,
-                    epoll >= 0.2.2,
-                    HTTP >= 4000.0.8,
-                    data-default >= 0.2,
-                    network >= 2.2.1.2,
-                    failure >= 0.0.0.1,
-                    utf8-string >= 0.3.4,
-                    containers >= 0.2.0.1
+                    hack,
+                    epoll,
+                    HTTP,
+                    data-default,
+                    network,
+                    failure,
+                    utf8-string,
+                    containers
   hs-source-dirs:   src
 
diff --git a/src/Hack/Handler/Epoll.hs b/src/Hack/Handler/Epoll.hs
--- a/src/Hack/Handler/Epoll.hs
+++ b/src/Hack/Handler/Epoll.hs
@@ -17,6 +17,7 @@
     ServerConf(..)
 ) where
 
+import Control.Applicative
 import Control.Concurrent
 import Control.Exception (Exception, bracket, finally)
 import Control.Failure
@@ -95,7 +96,7 @@
 
 parseEnv :: ServerConf -> Runtime -> Fd -> SockAddr -> IO Env
 parseEnv c r fd ra = withIBuffer r fd $ \b -> do
-    (hd, bd) <- readBuffer b >>= return . headBody
+    (hd, bd) <- headBody <$> readBuffer b
     header   <- try $ parseRequestHead . breakLines $ hd
     headerToEnv c header bd ra
 
@@ -106,7 +107,7 @@
     let rhost = mrhost ||| ""
         host' = lookupHeader HdrHost header ||| host conf
         body' = readBody bodyLen bdy
-    return $ Env
+    return Env
         { requestMethod = read . show $ meth
         , scriptName = ""
         , pathInfo = uriPath uri
@@ -124,17 +125,15 @@
         }
  where
     infixr 2 |||
-    (|||) m d = maybe d id m
+    (|||) = flip fromMaybe
 
     bodyLen = transferEnc ||| contentLen ||| Unknown
 
-    contentLen = do
-        cl <- lookupHeader HdrContentLength header
-        return . Len . abs . read $ cl
+    contentLen = (Len . abs . read) <$>
+        lookupHeader HdrContentLength header
 
-    transferEnc = do
-        tc <- lookupHeader HdrTransferEncoding header
-        if tc /= "identity" then return Chunked else return Unknown
+    transferEnc = (choose Chunked Unknown . (/= "identity")) <$>
+        lookupHeader HdrTransferEncoding header
 
 
 writeResponse :: Runtime -> Fd -> Response -> IO ()
@@ -188,6 +187,9 @@
 isIn :: (Eq a) => [a] -> a -> Bool
 isIn = flip elem
 
+choose :: a -> a -> Bool -> a
+choose x _ True  = x
+choose _ y False = y
 
 statusCode :: M.Map Int String
 statusCode = M.fromAscList