diff --git a/Network/Wai/Handler/Warp.hs b/Network/Wai/Handler/Warp.hs
--- a/Network/Wai/Handler/Warp.hs
+++ b/Network/Wai/Handler/Warp.hs
@@ -19,11 +19,7 @@
 --
 ---------------------------------------------------------
 
--- | A fast, light-weight HTTP server handler for WAI. Some random notes (a FAQ, if you will):
---
--- * When a 'ResponseFile' indicates a file which does not exist, an exception
---   is thrown. This will close the connection to the client as well. You should
---   handle file existance checks at the application level.
+-- | A fast, light-weight HTTP server handler for WAI.
 module Network.Wai.Handler.Warp
     ( -- * Run a Warp server
       run
@@ -60,7 +56,6 @@
     , T.initialize
 #if TEST
     , takeHeaders
-    , readInt
 #endif
     ) where
 
@@ -86,6 +81,7 @@
     , fromException, AsyncException (ThreadKilled)
     , bracketOnError
     , IOException
+    , try
     )
 import Control.Concurrent (forkIO)
 import Data.Maybe (fromMaybe, isJust)
@@ -115,10 +111,10 @@
 import Control.Monad (forever, when)
 import qualified Network.HTTP.Types as H
 import qualified Data.CaseInsensitive as CI
-import System.IO (hPutStrLn, stderr)
-import ReadInt (readInt64)
+import System.IO (hPrint, stderr)
 import qualified Data.IORef as I
 import Data.String (IsString (..))
+import qualified Data.ByteString.Lex.Integral as LI
 
 #if WINDOWS
 import Control.Concurrent (threadDelay)
@@ -198,7 +194,7 @@
         theBody addr = 
           bracketOnError
           (Network.Socket.socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr))
-          (sClose)
+          sClose
           (\sock -> do
               setSocketOption sock ReuseAddr 1
               bindSocket sock (addrAddress addr)
@@ -353,7 +349,7 @@
     let len0 =
             case lookup "content-length" heads of
                 Nothing -> 0
-                Just bs -> readInt bs
+                Just bs -> LI.readDecimal_ bs
     let serverName' = takeUntil 58 host -- ':'
     rbody <-
         if len0 == 0
@@ -511,29 +507,36 @@
     needsChunked hs = isChunked' && not (hasLength hs)
     isKeepAlive hs = isPersist && (isChunked' || hasLength hs)
     hasLength hs = isJust $ lookup "content-length" hs
+    sendHeader = connSendMany conn . L.toChunks . toLazyByteString
 
     sendResponse' :: Response -> ResourceT IO Bool
-    sendResponse' (ResponseFile s hs fp mpart) = liftIO $ do
-        (lengthyHeaders, cl) <-
-            case (readInt `fmap` lookup "content-length" hs, mpart) of
-                (Just cl, _) -> return (hs, cl)
-                (Nothing, Nothing) -> do
+    sendResponse' (ResponseFile s hs fp mpart) = do
+        eres <-
+            case (LI.readDecimal_ `fmap` lookup "content-length" hs, mpart) of
+                (Just cl, _) -> return $ Right (hs, cl)
+                (Nothing, Nothing) -> liftIO $ try $ do
                     cl <- P.fileSize `fmap` P.getFileStatus fp
                     return $ addClToHeaders cl
                 (Nothing, Just part) -> do
                     let cl = filePartByteCount part
-                    return $ addClToHeaders cl
-        connSendMany conn $ L.toChunks $ toLazyByteString $
-          headers version s lengthyHeaders False
-
-        T.tickle th
-
-        if not (hasBody s req) then return isPersist else do
-            case mpart of
-                Nothing   -> connSendFile conn fp 0 cl (T.tickle th)
-                Just part -> connSendFile conn fp (filePartOffset part) (filePartByteCount part) (T.tickle th)
-            T.tickle th
-            return isPersist
+                    return $ Right $ addClToHeaders cl
+        case eres of
+            Left (_ :: SomeException) -> sendResponse' $ responseLBS
+                H.status404
+                [("Content-Type", "text/plain")]
+                "File not found"
+            Right (lengthyHeaders, cl) -> liftIO $ do
+                let headers' = headers version s lengthyHeaders
+                sendHeader $ headers' False
+                T.tickle th
+                if hasBody s req then do
+                    case mpart of
+                        Nothing   -> connSendFile conn fp 0 cl (T.tickle th)
+                        Just part -> connSendFile conn fp (filePartOffset part) (filePartByteCount part) (T.tickle th)
+                    T.tickle th
+                    return isPersist
+                  else
+                    return isPersist
       where
         addClToHeaders cl = (("Content-Length", B.pack $ show cl):hs, fromIntegral cl)
 
@@ -544,10 +547,7 @@
                 T.tickle th) body
               return (isKeepAlive hs)
         | otherwise = liftIO $ do
-            connSendMany conn
-                $ L.toChunks
-                $ toLazyByteString
-                $ headers' False
+            sendHeader $ headers' False
             T.tickle th
             return isPersist
       where
@@ -559,8 +559,16 @@
                        `mappend` chunkedTransferTerminator
                   else headers' False `mappend` b
 
-    sendResponse' (ResponseSource s hs bodyFlush) =
-        response
+    sendResponse' (ResponseSource s hs bodyFlush)
+        | hasBody s req = do
+            let src = CL.sourceList [headers' needsChunked'] `mappend`
+                      (if needsChunked' then body C.$= chunk else body)
+            src C.$$ builderToByteString C.=$ connSink conn th
+            return $ isKeepAlive hs
+        | otherwise = liftIO $ do
+            sendHeader $ headers' False
+            T.tickle th
+            return isPersist
       where
         body = fmap (\x -> case x of
                         C.Flush -> flush
@@ -568,26 +576,12 @@
         headers' = headers version s hs
         -- FIXME perhaps alloca a buffer per thread and reuse that in all
         -- functions below. Should lessen greatly the GC burden (I hope)
-        response
-            | not (hasBody s req) = liftIO $ do
-                connSendMany conn
-                   $ L.toChunks $ toLazyByteString
-                   $ headers' False
-                T.tickle th
-                return (checkPersist req)
-            | otherwise = do
-                let src =
-                        CL.sourceList [headers' needsChunked'] `mappend`
-                        (if needsChunked' then body C.$= chunk else body)
-                src C.$$ builderToByteString C.=$ connSink conn th
-                return $ isKeepAlive hs
         needsChunked' = needsChunked hs
         chunk :: C.Conduit Builder IO Builder
         chunk = C.Conduit
             { C.conduitPush = push
             , C.conduitClose = close
             }
-
         conduit = C.Conduit push close
         push x = return $ C.Producing conduit [chunkedTransferEncoding x]
         close = return [chunkedTransferTerminator]
@@ -695,7 +689,7 @@
             Just x -> go x
             Nothing ->
                 when (go' $ fromException e) $
-                    hPutStrLn stderr $ show e
+                    hPrint stderr e
     , settingsTimeout = 30
     , settingsIntercept = const Nothing
     , settingsManager = Nothing
@@ -768,11 +762,6 @@
         then p
         else pos
 {-# INLINE checkCR #-}
-
-readInt :: Integral a => ByteString -> a
-readInt bs = fromIntegral $ readInt64 bs
-{-# INLINE readInt #-}
-
 
 -- | Call the inner function with a timeout manager.
 withManager :: Int -- ^ timeout in microseconds
diff --git a/ReadInt.hs b/ReadInt.hs
deleted file mode 100644
--- a/ReadInt.hs
+++ /dev/null
@@ -1,58 +0,0 @@
-{-# LANGUAGE OverloadedStrings, MagicHash, BangPatterns  #-}
-
--- Copyright     : Erik de Castro Lopo <erikd@mega-nerd.com>
--- License       : BSD3
-
-module ReadInt (readInt64) where
-
--- This function lives in its own file because the MagicHash pragma interacts
--- poorly with the CPP pragma.
-
-import Data.ByteString (ByteString)
-import Data.Int (Int64)
-import GHC.Prim
-import GHC.Types
-
-import qualified Data.ByteString.Char8 as B
-import qualified Data.Char as C
-
--- This function is used to parse the Content-Length field of HTTP headers and
--- is a performance hot spot. It should only be replaced with something
--- significantly and provably faster.
---
--- It needs to be able work correctly on 32 bit CPUs for file sizes > 2G so we
--- use Int64 here and then make a generic 'readInt' that allows conversion to
--- Int and Integer.
-
-readInt64 :: ByteString -> Int64
-readInt64 bs =
-        B.foldl' (\i c -> i * 10 + fromIntegral (mhDigitToInt c)) 0
-             $ B.takeWhile C.isDigit bs
-{- NOINLINE readInt64MH #-}
-
-data Table = Table !Addr#
-
-{- NOINLINE mhDigitToInt #-}
-mhDigitToInt :: Char -> Int
-mhDigitToInt (C# i) = I# (word2Int# (indexWord8OffAddr# addr (ord# i)))
-  where
-    !(Table addr) = table
-    table :: Table
-    table = Table
-        "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\
-        \\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"#
-
diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             1.1.0
+Version:             1.1.0.1
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             BSD3
 License-file:        LICENSE
@@ -29,6 +29,7 @@
                    , http-types                    >= 0.6      && < 0.7
                    , case-insensitive              >= 0.2
                    , unix-compat                   >= 0.2
+                   , bytestring-lexing             >= 0.4
                    , ghc-prim
   if flag(network-bytestring)
       build-depends: network               >= 2.2.1.5 && < 2.2.3
@@ -37,7 +38,6 @@
       build-depends: network               >= 2.3     && < 2.4
   Exposed-modules:   Network.Wai.Handler.Warp
   Other-modules:     Timeout
-                     ReadInt
                      Paths_warp
   ghc-options:       -Wall
   if os(windows)