diff --git a/Network/HTTP.hs b/Network/HTTP.hs
--- a/Network/HTTP.hs
+++ b/Network/HTTP.hs
@@ -1,5 +1,11 @@
 {-# LANGUAGE TypeSynonymInstances, FlexibleInstances, FlexibleContexts,
              DeriveDataTypeable #-}
+-- | This module provides facilities for implementing webservers, in a
+--   servelet-like style.  The general philosophy is that direct-http makes
+--   as few decisions as possible for the user code, allowing such things as
+--   URL routing and virtual-host policies to be implemented in any desired
+--   fashion.  It focuses on providing a robust transport layer which can
+--   integrate well with any higher layer.
 module Network.HTTP (
              -- * The monad
              HTTP,
@@ -124,6 +130,8 @@
     where
 
 import Control.Concurrent.Lifted
+import Control.Concurrent.MSem (MSem)
+import qualified Control.Concurrent.MSem as MSem
 import Control.Exception.Lifted
 import Control.Monad.Base
 import Control.Monad.Reader
@@ -147,6 +155,7 @@
 import GHC.IO.Exception (IOErrorType(..))
 import qualified Network.Socket as Network hiding (send, sendTo, recv, recvFrom)
 import qualified Network.Socket.ByteString as Network
+import Numeric
 import Prelude hiding (catch)
 import System.Daemonize
 import System.Environment
@@ -165,7 +174,7 @@
     httpStateErrorLogMaybeHandleMVar :: MVar (Maybe Handle),
     httpStateForkPrimitive :: IO () -> IO ThreadId,
     httpStateThreadSetMVar :: MVar (Set ThreadId),
-    httpStateThreadTerminationQSem :: QSem,
+    httpStateThreadTerminationMSem :: MSem Word,
     httpStateMaybeConnection :: Maybe HTTPConnection
   }
 
@@ -199,7 +208,7 @@
   | RequestContentNone
   | RequestContentClosed
   | RequestContentIdentity Int
-  | RequestContentChunked Bool Int
+  | RequestContentChunked Int
 
 data ResponseContentParameters
   = ResponseContentUninitialized
@@ -280,7 +289,7 @@
 httpFork action = do
   state <- getHTTPState
   let mvar = httpStateThreadSetMVar state
-      qsem = httpStateThreadTerminationQSem state
+      msem = httpStateThreadTerminationMSem state
   threadSet <- takeMVar mvar
   childThread <- liftBaseDiscard (httpStateForkPrimitive state)
     $ finally action
@@ -289,7 +298,7 @@
                 self <- myThreadId
                 let threadSet' = Set.delete self threadSet'
                 putMVar mvar threadSet'
-                signalQSem qsem)
+                liftBase $ MSem.signal msem)
   let threadSet' = Set.insert childThread threadSet
   putMVar mvar threadSet'
   return childThread
@@ -417,13 +426,13 @@
   errorLogMaybeHandleMVar <- newMVar errorLogMaybeHandle
   let forkPrimitive = serverParametersForkPrimitive parameters
   threadSetMVar <- newMVar Set.empty
-  threadTerminationQSem <- newQSem 0
+  threadTerminationMSem <- MSem.new 0
   let state = HTTPState {
                 httpStateAccessLogMaybeHandleMVar = accessLogMaybeHandleMVar,
                 httpStateErrorLogMaybeHandleMVar = errorLogMaybeHandleMVar,
                 httpStateForkPrimitive = forkPrimitive,
                 httpStateThreadSetMVar = threadSetMVar,
-                httpStateThreadTerminationQSem = threadTerminationQSem,
+                httpStateThreadTerminationMSem = threadTerminationMSem,
                 httpStateMaybeConnection = Nothing
               }
   if serverParametersDaemonize parameters
@@ -450,12 +459,12 @@
         threadWaitLoop = do
           state <- getHTTPState
           let mvar = httpStateThreadSetMVar state
-              qsem = httpStateThreadTerminationQSem state
+              msem = httpStateThreadTerminationMSem state
           threadSet <- readMVar mvar
           if Set.null threadSet
             then liftBase exitSuccess
             else do
-              waitQSem qsem
+              liftBase $ MSem.wait msem
               threadWaitLoop
 
 
@@ -1578,7 +1587,7 @@
             (_, Just _) -> (True, True)
   if hasContent
     then if chunked
-           then return $ RequestContentChunked False 0
+           then return $ RequestContentChunked 0
            else case maybeLength of
              Nothing -> return $ RequestContentNone
              Just length -> return $ RequestContentIdentity length
@@ -1630,10 +1639,10 @@
                 if not blocking || isAtLeastTargetLength highLevelBuffer
                   then return (highLevelBuffer', lowLevelBuffer', parameters')
                   else loop highLevelBuffer' lowLevelBuffer' parameters'
-              RequestContentChunked _ _ -> do
+              RequestContentChunked _ -> do
                  httpLog $ "Don't understand chunked."
                  throwIO UnexpectedEndOfInput
-                 -- TODO
+                 -- TODO IAK
   HTTPConnection { httpConnectionInputBufferMVar = lowLevelBufferMVar }
     <- getHTTPConnection
   lowLevelBuffer <- takeMVar lowLevelBufferMVar
@@ -2151,11 +2160,21 @@
           send bytestring
           return (buffer, parameters')
     ResponseContentChunked -> do
-      httpLog $ "Chunked not implemented."
-      putMVar parametersMVar parameters
-      putMVar bufferMVar buffer
-      throwIO UnexpectedEndOfInput
-      -- TODO
+      alreadySent <- takeMVar alreadySentMVar
+      if alreadySent
+        then return ()
+        else do
+          headersBuffer <- getHeadersBuffer
+          send headersBuffer
+      putMVar alreadySentMVar True
+      if BS.length bytestring > 0
+        then do
+          let lengthBuffer =
+                UTF8.fromString $ showHex (BS.length bytestring) "" ++ "\r\n"
+              crlfBuffer = UTF8.fromString "\r\n"
+          send $ BS.concat [lengthBuffer, bytestring, crlfBuffer]
+        else return ()
+      return (buffer, parameters)
   putMVar parametersMVar parameters
   putMVar bufferMVar buffer
 
@@ -2211,11 +2230,10 @@
           throwIO OutputIncomplete
         else return ()
     ResponseContentChunked -> do
-      httpLog $ "Chunked not implemented."
+      let emptyChunkBuffer = UTF8.fromString $ "0\r\n\r\n\r\n"
+      send emptyChunkBuffer
       putMVar parametersMVar parameters
       putMVar bufferMVar buffer
-      throwIO UnexpectedEndOfInput
-      -- TODO
   putMVar parametersMVar ResponseContentClosed
   putMVar bufferMVar BS.empty
 
diff --git a/direct-http.cabal b/direct-http.cabal
--- a/direct-http.cabal
+++ b/direct-http.cabal
@@ -1,5 +1,5 @@
 name: direct-http
-version: 0.5.0.1
+version: 0.5.1
 cabal-version: >= 1.10
 build-type: Simple
 license: BSD3
@@ -22,6 +22,9 @@
   to it, and makes several design decisions differently.  The biggest is the
   use of MonadControlBase for exceptions.
   .
+  Version 0.5.1: Uses SafeSemaphore, which is the future, rather than QSem
+  from base, which is deprecated.
+  .
   Version 0.5.0.1: This preliminary release is a preview to gauge community
   interest.  Not even all major features are implemented; things that exist
   only as stubs include encryption, compression, chunking, and reading back
@@ -42,5 +45,6 @@
                  direct-daemonize >= 3.0 && < 4,
                  transformers-base >= 0.4.1 && < 1,
                  lifted-base >= 0.1.1 && < 2,
-                 monad-control >= 0.3.1.3 && < 1
+                 monad-control >= 0.3.1.3 && < 1,
+                 SafeSemaphore >= 0.9.0 && < 1
   default-language: Haskell2010