diff --git a/lib/GHCup.hs b/lib/GHCup.hs
index 9d0cbff..3628bd3 100644
--- a/lib/GHCup.hs
+++ b/lib/GHCup.hs
@@ -77,6 +77,9 @@ import           System.Directory        hiding ( findFiles )
 import           System.Environment
 import           System.FilePath
 import           System.IO.Error
+#if defined(IS_WINDOWS)
+import           System.IO.Temp
+#endif
 import           Text.PrettyPrint.HughesPJClass ( prettyShow )
 import           Text.Regex.Posix
 
@@ -249,6 +252,22 @@ installPackedGHC :: ( MonadMask m
 #endif
                        ] m ()
 installPackedGHC dl msubdir inst ver = do
+#if defined(IS_WINDOWS)
+  lift $ $(logInfo) "Installing GHC (this may take a while)"
+
+  Dirs { tmpDir } <- lift getDirs
+  unpackDir <- liftIO $ emptyTempFile tmpDir "ghc"
+  liftIO $ rmFile unpackDir
+
+  liftE $ unpackToDir unpackDir dl
+
+  d <- case msubdir of
+    Just td -> liftE $ intoSubdir unpackDir td
+    Nothing -> pure unpackDir
+
+  liftIO $ Win32.moveFileEx d (Just inst) 0
+  liftIO $ rmPath unpackDir
+#else
   PlatformRequest {..} <- lift getPlatformReq
 
   -- unpack
@@ -264,6 +283,7 @@ installPackedGHC dl msubdir inst ver = do
   liftE $ runBuildAction tmpUnpack
                          (Just inst)
                          (installUnpackedGHC workdir inst ver)
+#endif
 
 
 -- | Install an unpacked GHC distribution. This only deals with the GHC
@@ -280,13 +300,6 @@ installUnpackedGHC :: ( MonadReader env m
                    -> FilePath      -- ^ Path to install to
                    -> Version       -- ^ The GHC version
                    -> Excepts '[ProcessError] m ()
-#if defined(IS_WINDOWS)
-installUnpackedGHC path inst _ = do
-  lift $ $(logInfo) "Installing GHC (this may take a while)"
-  -- windows bindists are relocatable and don't need
-  -- to run configure
-  liftIO $ copyDirectoryRecursive path inst
-#else
 installUnpackedGHC path inst ver = do
   PlatformRequest {..} <- lift getPlatformReq
 
@@ -309,7 +322,6 @@ installUnpackedGHC path inst ver = do
                    Nothing
   lEM $ make ["install"] (Just path)
   pure ()
-#endif
 
 
 -- | Installs GHC into @~\/.ghcup\/ghc/\<ver\>@ and places the
@@ -1495,6 +1507,7 @@ rmGhcupDirs = do
     , binDir
     , logsDir
     , cacheDir
+    , tmpDir
     } <- getDirs
 
   let envFilePath = baseDir </> "env"
@@ -1506,6 +1519,7 @@ rmGhcupDirs = do
   rmDir cacheDir
   rmDir logsDir
   rmBinDir   binDir
+  rmDir tmpDir
 #if defined(IS_WINDOWS)
   rmDir (baseDir </> "msys64")
 #endif
diff --git a/lib/GHCup/Types.hs b/lib/GHCup/Types.hs
index 79ea220..284b47d 100644
--- a/lib/GHCup/Types.hs
+++ b/lib/GHCup/Types.hs
@@ -384,6 +384,7 @@ data Dirs = Dirs
   , cacheDir :: FilePath
   , logsDir  :: FilePath
   , confDir  :: FilePath
+  , tmpDir   :: FilePath
   }
   deriving (Show, GHC.Generic)
 
diff --git a/lib/GHCup/Utils.hs b/lib/GHCup/Utils.hs
index fe2e4a0..b94b7e3 100644
--- a/lib/GHCup/Utils.hs
+++ b/lib/GHCup/Utils.hs
@@ -1086,19 +1086,14 @@ ensureGlobalTools = do
 
 -- | Ensure ghcup directory structure exists.
 ensureDirectories :: Dirs -> IO ()
-ensureDirectories dirs = do
-  let Dirs
-        { baseDir
-        , binDir
-        , cacheDir
-        , logsDir
-        , confDir
-        } = dirs
+ensureDirectories (Dirs baseDir binDir cacheDir logsDir confDir tmpDir) = do
   createDirRecursive' baseDir
+  createDirRecursive' (baseDir </> "ghc")
   createDirRecursive' binDir
   createDirRecursive' cacheDir
   createDirRecursive' logsDir
   createDirRecursive' confDir
+  createDirRecursive' tmpDir
   pure ()
 
 
diff --git a/lib/GHCup/Utils/Dirs.hs b/lib/GHCup/Utils/Dirs.hs
index 807bcc4..2bdb524 100644
--- a/lib/GHCup/Utils/Dirs.hs
+++ b/lib/GHCup/Utils/Dirs.hs
@@ -191,6 +191,15 @@ ghcupLogsDir = do
 #endif
 
 
+-- | Defaults to '~/.ghcup/tmp.
+--
+-- If 'GHCUP_USE_XDG_DIRS' is set (to anything),
+-- then uses 'XDG_DATA_HOME/ghcup/tmp' as per xdg spec.
+ghcupTmpDir :: IO FilePath
+ghcupTmpDir = ghcupBaseDir <&> (</> "tmp")
+
+
+
 getAllDirs :: IO Dirs
 getAllDirs = do
   baseDir  <- ghcupBaseDir
@@ -198,6 +207,7 @@ getAllDirs = do
   cacheDir <- ghcupCacheDir
   logsDir  <- ghcupLogsDir
   confDir  <- ghcupConfigDir
+  tmpDir   <- ghcupTmpDir
   pure Dirs { .. }