diff --git a/Win32-notify.cabal b/Win32-notify.cabal
index 85d0e57..9f363ca 100644
--- a/Win32-notify.cabal
+++ b/Win32-notify.cabal
@@ -12,7 +12,7 @@ build-type:     Simple
 cabal-version:  >= 1.8
 
 library
-  build-depends:   base, Win32, directory, containers >= 0.4.0.0
+  build-depends:   base >= 4.3.1.0 && < 5, Win32, directory, containers >= 0.4.0.0
   ghc-options:     -Wall -fno-warn-incomplete-patterns -fno-warn-unused-imports -threaded
   exposed-modules: System.Win32.Notify
   other-modules:   System.Win32.FileNotify
@@ -20,5 +20,5 @@ library
 
 executable simple
   main-is:       examples/simple/simple.hs
-  build-depends: base, directory, Win32-notify >= 0.1
+  build-depends: base >= 4.3.1.0 && < 5, directory, Win32-notify >= 0.1
   ghc-options:   -Wall -threaded
diff --git a/src/System/Win32/Notify.hs b/src/System/Win32/Notify.hs
index 98c1993..219f4b5 100644
--- a/src/System/Win32/Notify.hs
+++ b/src/System/Win32/Notify.hs
@@ -1,13 +1,14 @@
 module System.Win32.Notify
-  ( initWatchManager
-  , killWatchManager
-  , watchDirectory
-  , watch
-  , Event(..)
+  ( Event(..)
   , EventVariety(..)
   , Handler
   , WatchId(..)
   , WatchManager(..)
+  , initWatchManager
+  , killWatch
+  , killWatchManager
+  , watch
+  , watchDirectory
     ) where
 
 import Control.Concurrent
@@ -16,6 +17,7 @@ import Data.Bits
 import Data.List (intersect)
 import Data.Map (Map)
 import System.Directory
+import System.Win32 (closeHandle)
 import System.Win32.File
 import System.Win32.FileNotify
 import qualified Data.Map as Map
@@ -57,7 +59,7 @@ data Event
 
 type Handler = Event -> IO ()
 
-data WatchId = WatchId ThreadId ThreadId deriving (Eq, Ord, Show)
+data WatchId = WatchId ThreadId ThreadId Handle deriving (Eq, Ord, Show)
 type WatchMap = Map WatchId Handler
 data WatchManager = WatchManager (MVar WatchMap)
 
@@ -69,14 +71,7 @@ initWatchManager =  do
 killWatchManager :: WatchManager -> IO ()
 killWatchManager (WatchManager mvarMap) = do
   watchMap <- readMVar mvarMap
-  flip mapM_ (Map.keys watchMap) $ killThreads
-  where
-    killThreads :: WatchId -> IO ()
-    killThreads (WatchId tid1 tid2)
-      | tid1 == tid2 = killThread tid1
-      | otherwise    = do
-        killThread tid1
-        killThread tid2
+  flip mapM_ (Map.keys watchMap) $ killWatch
 
 varietiesToFnFlags :: [EventVariety] -> FileNotificationFlag
 varietiesToFnFlags = foldl (.|.) 0 . map evToFnFlag'
@@ -98,7 +93,7 @@ watchDirectory (WatchManager mvarMap) dir watchSubTree varieties handler = do
   chanEvents <- newChan
   tid1 <- forkIO $ dispatcher chanEvents
   tid2 <- forkIO $ osEventsReader watchHandle chanEvents
-  modifyMVar_ mvarMap $ \watchMap -> return (Map.insert (WatchId tid1 tid2) handler watchMap)
+  modifyMVar_ mvarMap $ \watchMap -> return (Map.insert (WatchId tid1 tid2 watchHandle) handler watchMap)
   return (WatchId tid1 tid2)
   where
     dispatcher :: Chan [Event] -> IO ()
@@ -120,7 +115,7 @@ watch (WatchManager mvarMap) dir watchSubTree varieties = do
   watchHandle <- getWatchHandle dir
   chanEvents <- newChan
   tid <- forkIO $ osEventsReader watchHandle chanEvents
-  modifyMVar_ mvarMap $ \watchMap -> return (Map.insert (WatchId tid tid) (\_ -> return ()) watchMap)
+  modifyMVar_ mvarMap $ \watchMap -> return (Map.insert (WatchId tid tid watchHandle) (\_ -> return ()) watchMap)
   return ((WatchId tid tid), chanEvents)
   where
     osEventsReader :: Handle -> Chan [Event] -> IO ()
@@ -129,6 +124,12 @@ watch (WatchManager mvarMap) dir watchSubTree varieties = do
       writeChan chanEvents events
       osEventsReader watchHandle chanEvents
 
+killWatch :: WatchId -> IO ()
+killWatch (WatchId tid1 tid2 handle) = do
+    killThread tid1
+    if tid1 != tid2 then killThread tid2 else void
+    closeHandle handle
+
 eventToVariety :: Event -> EventVariety
 eventToVariety event = case event of
   Created  _ _   -> Create