diff --git a/Network/IHttp/Header.hs b/Network/IHttp/Header.hs
--- a/Network/IHttp/Header.hs
+++ b/Network/IHttp/Header.hs
@@ -21,7 +21,6 @@
 
 import qualified Data.ByteString as B
 import qualified Data.Map as M
-import Control.Applicative
 import Data.ByteString (ByteString)
 import Data.ByteString.Char8 ()
 import Data.Enumerator as E
@@ -51,8 +50,9 @@
 enumHeaders :: forall b m. Monad m => HeaderMap -> Enumerator ByteString m b
 enumHeaders headers = enum
     where
-    format :: ByteString -> ByteString -> [ByteString] -> [ByteString]
-    format header content rest = header : ": " : content : "\r\n" : rest
+    format :: HeaderKey -> ByteString -> [ByteString] -> [ByteString]
+    format (HeaderKey headerStr) content rest =
+        headerStr : ": " : content : "\r\n" : rest
 
     enum :: Enumerator ByteString m b
     enum (Continue k) = k (Chunks . M.foldrWithKey format [] $ headers)
@@ -68,27 +68,27 @@
 
 httpHeader ::
     forall m. Monad m =>
-    Int -> Iteratee ByteString m (Maybe (ByteString, ByteString))
+    Int -> Iteratee ByteString m (Maybe (HeaderKey, ByteString))
 httpHeader n = do
     line <- EL.head >>=
             maybe (throwError $ InvalidHeaderError "Premature end of stream") return
     if B.null line
       then return Nothing
       else do
-          (hdrName, hdrTxt) <- parseIter httpFirstHeaderP InvalidHeaderError line
-          Just <$> continue (loop hdrName (B.take n hdrTxt))
+          (hdrName, hdrTxt') <- parseIter httpFirstHeaderP InvalidHeaderError line
+          hdrTxt <- continue (loop (B.take n hdrTxt'))
+          return $ Just (hdrName, hdrTxt)
 
     where
-    loop :: ByteString -> ByteString -> Stream ByteString ->
-            Iteratee ByteString m (ByteString, ByteString)
-    loop hdrName hdrTxt EOF = yield (hdrName, hdrTxt) EOF
-    loop hdrName hdrTxt (Chunks []) = continue (loop hdrName hdrTxt)
-    loop hdrName hdrTxt' ch@(Chunks (line:lines)) =
+    loop :: ByteString -> Stream ByteString -> Iteratee ByteString m ByteString
+    loop hdrTxt EOF = yield hdrTxt EOF
+    loop hdrTxt (Chunks []) = continue (loop hdrTxt)
+    loop hdrTxt' ch@(Chunks (line:lines)) =
         let (pfx, sfx) = B.span (\c -> c == 32 || c == 9) line
             hdrTxt = B.take n $ B.append (B.snoc hdrTxt' 32) sfx
         in if B.null pfx
-             then yield (hdrName, hdrTxt') ch
-             else hdrTxt `seq` loop hdrName hdrTxt (Chunks lines)
+             then yield hdrTxt' ch
+             else hdrTxt `seq` loop hdrTxt (Chunks lines)
 
 
 -- | Get the headers of an HTTP request from a 'netLinesEmpty'-splitted
diff --git a/Network/IHttp/Parsers.hs b/Network/IHttp/Parsers.hs
--- a/Network/IHttp/Parsers.hs
+++ b/Network/IHttp/Parsers.hs
@@ -28,7 +28,6 @@
 import Control.ContStuff
 import Data.Attoparsec.Char8 as P
 import Data.ByteString (ByteString)
-import Network.IHttp.Tools
 import Network.IHttp.Types
 
 
@@ -55,12 +54,12 @@
           _                            -> empty <?> "Invalid response code"
 
 
--- | Parse first HTTP header line.
+-- | Parse initial HTTP header line.
 
-httpFirstHeaderP :: Parser (ByteString, ByteString)
+httpFirstHeaderP :: Parser (HeaderKey, ByteString)
 httpFirstHeaderP = do
     (,)
-    <$> (BC.map asciiToUpper <$> httpTokenP) <* string ": "
+    <$> (headerKey <$> httpTokenP) <* string ": "
     <*> messageP
     <?> "initial header line"
 
diff --git a/Network/IHttp/Request.hs b/Network/IHttp/Request.hs
--- a/Network/IHttp/Request.hs
+++ b/Network/IHttp/Request.hs
@@ -76,7 +76,10 @@
 
 mkGetRequest :: ByteString -> ByteString -> Request
 mkGetRequest domain uri =
-    Request { requestHeaders = M.singleton "Host" domain,
+    Request { requestHeaders =
+                  M.insert "CONNECTION" "CLOSE" .
+                  M.insert "HOST" domain $
+                  M.empty,
               requestMethod = GetMethod,
               requestUri = uri,
               requestVersion = Http1_1 }
diff --git a/Network/IHttp/Simple.hs b/Network/IHttp/Simple.hs
--- a/Network/IHttp/Simple.hs
+++ b/Network/IHttp/Simple.hs
@@ -15,7 +15,8 @@
       -- * Iteratees
       getRequest,
       getResponse,
-      httpRequest
+      httpRequest,
+      okRequest
     )
     where
 
@@ -75,3 +76,16 @@
 httpRequest cfg h req = do
     tryIO . run_ $ enumRequest req $$ iterHandleTimeout (httpTimeout cfg) h
     getResponse cfg
+
+
+-- | Send a request to the given output handle and return its response.
+-- If the response code is anything other than 200, throw a
+-- 'ResponseNotOkError' iteratee exception.
+
+okRequest ::
+    MonadIO m =>
+    HttpConfig -> Handle -> Request -> Iteratee ByteString m Response
+okRequest cfg h req = do
+    resp <- httpRequest cfg h req
+    when (responseCode resp /= 200) (throwError $ ResponseNotOkError resp)
+    return resp
diff --git a/Network/IHttp/Tools.hs b/Network/IHttp/Tools.hs
--- a/Network/IHttp/Tools.hs
+++ b/Network/IHttp/Tools.hs
@@ -20,10 +20,7 @@
 
       -- * Printing tools
       showMethod,
-      showVersion,
-
-      -- * Character tools
-      asciiToUpper
+      showVersion
     )
     where
 
@@ -32,19 +29,10 @@
 import Data.Attoparsec.Char8 as P
 import Data.ByteString as B
 import Data.ByteString.Char8 ()
-import Data.Char
 import Data.Enumerator as E
 import Data.List as L
 import Network.IHttp.Types
 import Text.Printf
-
-
--- | Fast ASCII version of 'toUpper'.
-
-asciiToUpper :: Char -> Char
-asciiToUpper c
-    | c >= 'a' && c <= 'z' = chr $ ord c - 0x20
-    | otherwise            = c
 
 
 -- | Runs the first computation and then the second, even if the first
diff --git a/Network/IHttp/Types.hs b/Network/IHttp/Types.hs
--- a/Network/IHttp/Types.hs
+++ b/Network/IHttp/Types.hs
@@ -7,7 +7,7 @@
 --
 -- Types for ihttp.
 
-{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveDataTypeable, GeneralizedNewtypeDeriving #-}
 
 module Network.IHttp.Types
     ( -- * Protocol data
@@ -17,15 +17,26 @@
       Request(..),
       Response(..),
 
+      -- * Header keys
+      HeaderKey(..),
+      headerKey,
+      recaseHeaderKey,
+
       -- * Miscellaneous types
       HttpError(..)
     )
     where
 
+import qualified Data.ByteString as B
+import qualified Data.ByteString.Char8 as BC
+import Control.Arrow
 import Control.Exception as Ex
 import Data.ByteString.Char8 (ByteString)
+import Data.Data
 import Data.Map (Map)
-import Data.Typeable
+import Data.Monoid
+import Data.String
+import Text.Printf
 
 
 -- TODO: Common HTTP headers with correct types.
@@ -38,16 +49,44 @@
 --     }
 
 
+-- | A HTTP header key.  This is just a 'ByteString', but with
+-- case-insensitive ordering and a pretty 'IsString' instance.
+
+newtype HeaderKey = HeaderKey { getHeaderKey :: ByteString }
+    deriving (Data, Monoid, Read, Typeable)
+
+instance Eq HeaderKey where
+    HeaderKey str1 == HeaderKey str2 =
+        B.map wordToUpper str1 == B.map wordToUpper str2
+
+instance IsString HeaderKey where
+    fromString = HeaderKey . recaseHeaderKey . BC.pack
+
+instance Ord HeaderKey where
+    compare (HeaderKey str1) (HeaderKey str2) =
+        compare (caseConvert str1) (caseConvert str2)
+
+        where
+        caseConvert :: ByteString -> ByteString
+        caseConvert = B.map wordToUpper
+
+instance Show HeaderKey where
+    show = ("HeaderKey " ++) . show . getHeaderKey
+
+
 -- | Map of HTTP headers.
 
-type HeaderMap = Map ByteString ByteString
+type HeaderMap = Map HeaderKey ByteString
 
 
 -- | HTTP error.
 
 data HttpError
+    -- | Non-OK response.
+    = ResponseNotOkError { httpErrorResponse :: Response }
+
     -- | Invalid headers from client/server.
-    = InvalidHeaderError { httpErrorMessage :: String }
+    | InvalidHeaderError { httpErrorMessage :: String }
 
     -- | Invalid requests from client.
     | InvalidRequestError { httpErrorMessage :: String }
@@ -62,6 +101,10 @@
 instance Exception HttpError
 
 instance Show HttpError where
+    show (ResponseNotOkError resp)     =
+        let code = responseCode resp
+            msg  = responseMessage resp
+        in printf "Non-OK response: %i %s" code (BC.unpack msg)
     show (InvalidHeaderError msg)      = "Invalid HTTP header: " ++ msg
     show (InvalidRequestError msg)     = "Invalid HTTP request: " ++ msg
     show (InvalidResponseError msg)    = "Invalid HTTP response: " ++ msg
@@ -114,3 +157,33 @@
       responseVersion :: HttpVersion  -- ^ Protocol version of response.
     }
     deriving (Eq, Read, Show)
+
+
+-- | Turn a 'ByteString' with 'recaseHeaderKey' case conversion to a
+-- 'HeaderKey'.
+
+headerKey :: ByteString -> HeaderKey
+headerKey = HeaderKey . recaseHeaderKey
+
+
+-- | Convert an arbitrary case header key to dashed camel case
+-- ("content-type" -> "Content-Type").
+
+recaseHeaderKey :: ByteString -> ByteString
+recaseHeaderKey =
+    B.intercalate (BC.singleton '-') .
+    map (maybe B.empty (uncurry B.cons . (wordToUpper *** B.map wordToLower)) .
+         B.uncons) .
+    BC.split '-'
+
+
+-- | Convert upper case characters to lower case (ASCII).
+
+wordToLower :: (Num a, Ord a) => a -> a
+wordToLower c = if c >= 65 && c <= 90 then c + 32 else c
+
+
+-- | Convert lower case characters to upper case (ASCII).
+
+wordToUpper :: (Num a, Ord a) => a -> a
+wordToUpper c = if c >= 97 && c <= 122 then c - 32 else c
diff --git a/Test.hs b/Test.hs
new file mode 100644
--- /dev/null
+++ b/Test.hs
@@ -0,0 +1,37 @@
+-- |
+-- Module:     Main
+-- Copyright:  (c) 2010 Ertugrul Soeylemez
+-- License:    BSD3
+-- Maintainer: Ertugrul Soeylemez <es@ertes.de>
+-- Stability:  experimental
+--
+-- ihttp test program.
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Main where
+
+import qualified Data.ByteString.Char8 as BC
+import qualified Data.Map as M
+import Control.ContStuff
+import Data.Enumerator as E
+import Data.Enumerator.Binary as EB
+import Data.Enumerator.NetLines
+import Network
+import Network.IHttp
+import System.IO
+
+
+main :: IO ()
+main = do
+    h <- connectTo "127.0.0.1" (PortNumber 80)
+    hSetBuffering h NoBuffering
+    run_ $ enumHandleSession 4096 60000 60000 h $$ do
+        resp <- okRequest defHttpConfig h (mkGetRequest "ertes.de" "/")
+        liftIO (print resp)
+        cnt <- maybe EB.consume EB.take $ do
+                   lenStr <- M.lookup "CONTENT-LENGTH" (responseHeaders resp)
+                   (len, _) <- BC.readInteger lenStr
+                   return len
+        liftIO (print cnt)
+    hClose h
diff --git a/ihttp.cabal b/ihttp.cabal
--- a/ihttp.cabal
+++ b/ihttp.cabal
@@ -1,5 +1,5 @@
 Name:          ihttp
-Version:       0.2.2
+Version:       0.3.0
 Category:      Network
 Synopsis:      Incremental HTTP iteratee
 Maintainer:    Ertugrul Söylemez <es@ertes.de>
@@ -21,9 +21,9 @@
     base >= 4 && <= 5,
     bytestring >= 0.9.1.7,
     containers >= 0.4.0.0,
-    contstuff >= 1.2.4,
+    contstuff >= 1.2.6,
     enumerator >= 0.4.7,
-    netlines >= 0.4.3
+    netlines >= 1.0.0
   GHC-Options:   -W
   Exposed-modules:
     Network.IHttp
@@ -35,9 +35,9 @@
     Network.IHttp.Tools
     Network.IHttp.Types
 
--- Executable ihttp-test
---   Build-depends:
---     base >= 4 && <= 5,
---     network >= 2.2.1.10
---   Main-is: Test.hs
---   GHC-Options: -W
+Executable ihttp-test
+  Build-depends:
+    base >= 4 && <= 5,
+    network >= 2.2.1.10
+  Main-is: Test.hs
+  GHC-Options: -W