diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 3.0.4
+
+Added `setFork`.
+
 ## 3.0.3
 
 Modify flushing of request bodies. Previously, regardless of the size of the
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
@@ -1,4 +1,5 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE RankNTypes #-}
 {-# OPTIONS_GHC -fno-warn-deprecations #-}
 
 ---------------------------------------------------------
@@ -42,6 +43,7 @@
   , setInstallShutdownHandler
   , setServerName
   , setMaximumBodyFlush
+  , setFork
     -- ** Getters
   , getPort
   , getHost
@@ -228,3 +230,14 @@
 setMaximumBodyFlush x y
     | Just x' <- x, x' < 0 = error "setMaximumBodyFlush: must be positive"
     | otherwise = y { settingsMaximumBodyFlush = x }
+
+-- | Code to fork a new thread to accept a connection.
+--
+-- This may be useful if you need OS bound threads, or if
+-- you wish to develop an alternative threading model.
+--
+-- Default: void . forkIOWithUnmask
+--
+-- Since 3.0.4
+setFork :: (((forall a. IO a -> IO a) -> IO ()) -> IO ()) -> Settings -> Settings
+setFork fork' s = s { settingsFork = fork' }
diff --git a/Network/Wai/Handler/Warp/Run.hs b/Network/Wai/Handler/Warp/Run.hs
--- a/Network/Wai/Handler/Warp/Run.hs
+++ b/Network/Wai/Handler/Warp/Run.hs
@@ -7,7 +7,7 @@
 module Network.Wai.Handler.Warp.Run where
 
 import Control.Arrow (first)
-import Control.Concurrent (threadDelay, forkIOWithUnmask)
+import Control.Concurrent (threadDelay)
 import qualified Control.Concurrent as Conc (yield)
 import Control.Exception as E
 import Control.Monad (when, unless, void)
@@ -225,7 +225,7 @@
      -> T.Manager
      -> Counter
      -> IO ()
-fork set mkConn addr app dc fc tm counter = void $ forkIOWithUnmask $ \unmask ->
+fork set mkConn addr app dc fc tm counter = settingsFork set $ \ unmask ->
     -- Run the connection maker to get a new connection, and ensure
     -- that the connection is closed. If the mkConn call throws an
     -- exception, we will leak the connection. If the mkConn call is
diff --git a/Network/Wai/Handler/Warp/Settings.hs b/Network/Wai/Handler/Warp/Settings.hs
--- a/Network/Wai/Handler/Warp/Settings.hs
+++ b/Network/Wai/Handler/Warp/Settings.hs
@@ -1,10 +1,12 @@
 {-# LANGUAGE OverloadedStrings, ScopedTypeVariables, ViewPatterns #-}
-{-# LANGUAGE PatternGuards #-}
+{-# LANGUAGE PatternGuards, RankNTypes #-}
+{-# LANGUAGE ImpredicativeTypes #-}
 
 module Network.Wai.Handler.Warp.Settings where
 
 import Control.Exception
-import Control.Monad (when)
+import Control.Monad (when, void)
+import Control.Concurrent (forkIOWithUnmask)
 import qualified Data.Text as T
 import qualified Data.Text.IO as TIO
 import Data.Streaming.Network (HostPreference)
@@ -52,6 +54,17 @@
       -- Default: do nothing.
       --
       -- Since 1.3.6
+
+    , settingsFork :: ((forall a. IO a -> IO a) -> IO ()) -> IO ()
+      -- ^ Code to fork a new thread to accept a connection.
+      --
+      -- This may be useful if you need OS bound threads, or if
+      -- you wish to develop an alternative threading model.
+      --
+      -- Default: void . forkIOWithUnmask
+      --
+      -- Since 3.0.4
+
     , settingsNoParsePath :: Bool
       -- ^ Perform no parsing on the rawPathInfo.
       --
@@ -85,6 +98,7 @@
     , settingsManager = Nothing
     , settingsFdCacheDuration = 10
     , settingsBeforeMainLoop = return ()
+    , settingsFork = void . forkIOWithUnmask
     , settingsNoParsePath = False
     , settingsInstallShutdownHandler = const $ return ()
     , settingsServerName = S8.pack $ "Warp/" ++ showVersion Paths_warp.version
diff --git a/Network/Wai/Handler/Warp/Windows.hs b/Network/Wai/Handler/Warp/Windows.hs
--- a/Network/Wai/Handler/Warp/Windows.hs
+++ b/Network/Wai/Handler/Warp/Windows.hs
@@ -10,8 +10,7 @@
 import Control.Monad
 
 windowsThreadBlockHack :: IO a -> IO a
-windowsThreadBlockHack act = 
-  do
+windowsThreadBlockHack act = do
     var <- newEmptyMVar :: IO (MVar (Either SomeException a))
     void . forkIO $ try act >>= putMVar var
     res <- takeMVar var
diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             3.0.3
+Version:             3.0.4
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             MIT
 License-file:        LICENSE