diff --git a/src/Crypt/SHA256.hs b/src/Crypt/SHA256.hs
index 69a8a4c..606f2ad 100644
--- a/src/Crypt/SHA256.hs
+++ b/src/Crypt/SHA256.hs
@@ -20,9 +20,10 @@ import Numeric (showHex)
 import Foreign.C.String ( withCString )
 import Data.ByteString.Unsafe (unsafeUseAsCStringLen)
 import qualified Data.ByteString as B
+import qualified System.IO.Unsafe as U
 
 sha256sum :: B.ByteString -> String
-sha256sum p = unsafePerformIO $
+sha256sum p = U.unsafePerformIO $
               withCString (take 64 $ repeat 'x') $ \digestCString ->
               unsafeUseAsCStringLen p $ \(ptr,n) ->
               do let digest = castPtr digestCString :: Ptr Word8
diff --git a/src/Darcs/Commands/Get.hs b/src/Darcs/Commands/Get.hs
index e450d28..6b51915 100644
--- a/src/Darcs/Commands/Get.hs
+++ b/src/Darcs/Commands/Get.hs
@@ -157,7 +157,8 @@ copyRepoAndGoToChosenVersion opts repodir rfsource = do
   copyRepo
   withRepository opts ((RepoJob $ \repository -> goToChosenVersion repository opts) :: RepoJob ())
   putInfo opts $ text "Finished getting."
-      where copyRepo =
+      where copyRepo :: IO ()
+            copyRepo =
                 withRepository opts $ RepoJob $ \repository ->
                   if formatHas HashedInventory rfsource
                    then do
diff --git a/src/Darcs/Global.hs b/src/Darcs/Global.hs
index 9792bf0..e17f071 100644
--- a/src/Darcs/Global.hs
+++ b/src/Darcs/Global.hs
@@ -60,8 +60,9 @@ module Darcs.Global
 import Control.Applicative ( (<$>), (<*>) )
 import Control.Monad ( when )
 import Control.Concurrent.MVar
-import Control.Exception.Extensible ( bracket_, catch, catchJust, SomeException
-                                    , block, unblock
+import Control.Exception.Extensible as E
+                                    ( bracket_, catch, catchJust, SomeException
+                                    , mask
                                     )
 import Data.IORef ( IORef, newIORef, readIORef, writeIORef )
 import Data.IORef ( modifyIORef )
@@ -106,12 +107,12 @@ withAtexit prog =
         exit
         prog
   where
-    exit = block $ do
+    exit = E.mask $ \restore -> do
         Just actions <- swapMVar atexitActions Nothing
         -- from now on atexit will not register new actions
-        mapM_ runAction actions
-    runAction action =
-        catch (unblock action) $ \(exn :: SomeException) -> do
+        mapM_ (runAction restore) actions
+    runAction restore action =
+        catch (restore action) $ \(exn :: SomeException) -> do
             hPutStrLn stderr $ "Exception thrown by an atexit registered action:"
             hPutStrLn stderr $ show exn
 
diff --git a/src/Darcs/SignalHandler.hs b/src/Darcs/SignalHandler.hs
index ac0f526..d0ef162 100644
--- a/src/Darcs/SignalHandler.hs
+++ b/src/Darcs/SignalHandler.hs
@@ -26,8 +26,8 @@ import Prelude hiding ( catch )
 import System.IO.Error ( isUserError, ioeGetErrorString, ioeGetFileName )
 import System.Exit ( exitWith, ExitCode ( ExitFailure ) )
 import Control.Concurrent ( ThreadId, myThreadId )
-import Control.Exception.Extensible
-            ( catch, throw, throwTo, block, unblock,
+import Control.Exception.Extensible as E
+            ( catch, throw, throwTo, mask,
               Exception(..), SomeException(..), IOException )
 import System.Posix.Files ( getFdStatus, isNamedPipe )
 import System.Posix.IO ( stdOutput )
@@ -128,8 +128,8 @@ catchUserErrors comp handler = catch comp handler'
          | otherwise                             = throw ioe
 
 withSignalsBlocked :: IO a -> IO a
-withSignalsBlocked job = block (job >>= \r ->
-                           unblock(return r) `catchSignal` couldnt_do r)
+withSignalsBlocked job = E.mask $ \restore -> (job >>= \r ->
+                           restore (return r) `catchSignal` couldnt_do r)
     where couldnt_do r s | s == sigINT = oops "interrupt" r
                          | s ==  sigHUP = oops "HUP" r
                          | s ==  sigABRT = oops "ABRT" r
diff --git a/src/Darcs/Test/Patch/Info.hs b/src/Darcs/Test/Patch/Info.hs
index fd27fb3..b35cfef 100644
--- a/src/Darcs/Test/Patch/Info.hs
+++ b/src/Darcs/Test/Patch/Info.hs
@@ -28,7 +28,6 @@ import Data.Maybe ( isNothing )
 import Data.Text as T ( find, any )
 import Data.Text.Encoding ( decodeUtf8With )
 import Data.Text.Encoding.Error ( lenientDecode )
-import Foreign ( unsafePerformIO )
 import Test.QuickCheck ( Arbitrary(arbitrary), oneof, listOf, choose, shrink
                        , Gen )
 import Test.Framework.Providers.QuickCheck2 ( testProperty )
@@ -39,6 +38,8 @@ import Darcs.Patch.Info ( PatchInfo(..), patchinfo,
                           piLog, piAuthor, piName )
 import ByteStringUtils ( decodeLocale, packStringToUTF8, unpackPSFromUTF8 )
 
+import qualified System.IO.Unsafe as U
+
 testSuite :: Test
 testSuite = testGroup "Darcs.Patch.Info"
   [ metadataDecodingTest
@@ -86,7 +87,7 @@ instance Arbitrary UTF8PatchInfo where
         sa <- shrink (piAuthor pi)
         sl <- shrink (filter (not . isPrefixOf "Ignore-this:") (piLog pi))
         return (UTF8PatchInfo
-                   (unsafePerformIO $ patchinfo sn
+                   (U.unsafePerformIO $ patchinfo sn
                                           (BC.unpack (_piDate pi)) sa sl))
 
 instance Arbitrary UTF8OrNotPatchInfo where
@@ -101,7 +102,7 @@ arbitraryUTF8Patch =
        d <- arbitrary
        a <- asString `fmap` arbitrary
        l <- (lines . asString) `fmap` arbitrary
-       return $ unsafePerformIO $ patchinfo n d a l
+       return $ U.unsafePerformIO $ patchinfo n d a l
 
 -- | Generate arbitrary patch metadata that has totally arbitrary byte strings
 --   as its name, date, author and log.