diff --git a/orc.cabal b/orc.cabal
--- a/orc.cabal
+++ b/orc.cabal
@@ -1,5 +1,5 @@
 name:               orc
-version:            1.2.1.2
+version:            1.2.1.3
 synopsis:           Orchestration-style co-ordination EDSL
 description:        Provides an EDSL with Orc primitives.
 category:           Web
@@ -8,16 +8,16 @@
 author:             John Launchbury, Trevor Elliott
 maintainer:         John Launchbury, Trevor Elliott
 Copyright:          (c) 2008-2010, Galois, Inc.
-cabal-version:      >= 1.2.0
+cabal-version:      >= 1.10
 build-type:         Simple
 
 
 Library
-  Extensions:       GeneralizedNewtypeDeriving
+  Default-language: Haskell2010
   Build-Depends:    base    >= 4.2.0.0  && < 5.0,
                     stm     >= 2.2.0.0  && < 2.5,
                     process >= 1.0.1.0  && < 1.2,
-                    mtl     >= 2.0.1.0  && < 2.1,
+                    mtl     >= 2.0.1.0,
                     monadIO >= 0.10.1.1 && < 0.11,
                     deepseq >= 1.1.0.0  && < 1.4
   Exposed-modules:  Control.Concurrent.Hierarchical
@@ -26,11 +26,20 @@
                     Orc
   Hs-Source-Dirs:   src
   Ghc-Options:      -Wall
+  if (impl(ghc >= 7))
+    CPP-Options:    -D__GHC_BLOCK_DEPRECATED__
 
 Executable orc
-  Extensions:       GeneralizedNewtypeDeriving
+  Default-language: Haskell2010
   main-is:          test.hs
-  Build-Depends:    deepseq,
+  Build-Depends:    base    >= 4.2.0.0  && < 5.0,
+                    stm     >= 2.2.0.0  && < 2.5,
+                    process >= 1.0.1.0  && < 1.2,
+                    mtl     >= 2.0.1.0,
+                    monadIO >= 0.10.1.1 && < 0.11,
+                    deepseq >= 1.1.0.0  && < 1.4,
                     random
   hs-source-dirs:   src src/Examples
-  ghc-options:      -threaded
+  Ghc-Options:      -threaded
+  if (impl(ghc >= 7))
+    CPP-Options:    -D__GHC_BLOCK_DEPRECATED__
diff --git a/src/Control/Concurrent/Hierarchical.hs b/src/Control/Concurrent/Hierarchical.hs
--- a/src/Control/Concurrent/Hierarchical.hs
+++ b/src/Control/Concurrent/Hierarchical.hs
@@ -12,6 +12,7 @@
 -- when they are killed.
 
 {-# OPTIONS_GHC -fno-warn-unused-do-bind #-}
+{-# LANGUAGE CPP #-}
 
 
 module Control.Concurrent.Hierarchical (
@@ -21,12 +22,12 @@
   , runHIO          -- :: HIO b -> IO b
   , newPrimGroup
   , newGroup     -- :: HIO Group
-  
+
   , local
   , close
   , Group
   , finished
-  
+
   ) where
 
 import Control.Monad
@@ -67,7 +68,7 @@
 
 ---------------------------------------------------------------------------
 -- ^ The thread-registry environment is a hierarchical structure of local
--- thread neighborhoods. 
+-- thread neighborhoods.
 
 -- | A thread 'Group' keeps tracks of its inhabitants, which may be
 -- threads or other 'Group's.
@@ -81,14 +82,23 @@
 
 
 instance HasFork HIO where
-  fork hio = HIO $ \w -> block $ do
+#ifdef __GHC_BLOCK_DEPRECATED__
+  fork hio = HIO $ \w -> mask $ \ restore -> do
     when countingThreads incrementThreadCount
     increment w
+    fork (do tid <- myThreadId
+             register (Thread tid) w
+             restore (hio `inGroup` w)
+          `finally`
+          decrement w)
+#else
+  fork hio = HIO $ \w -> block $ do
     fork (block (do tid <- myThreadId
                     register (Thread tid) w
                     unblock (hio `inGroup` w))
-          `finally` 
-            decrement w)
+          `finally`
+          decrement w)
+#endif
 
 
 -- | Creates a new thread group and registers the current environment's
@@ -123,7 +133,7 @@
 runHIO :: HIO b -> IO ()
 runHIO hio = do
     w <- newPrimGroup
-    r <- hio `inGroup` w
+    _r <- hio `inGroup` w
     isZero w
     when countingThreads printThreadReport
     return ()
@@ -165,18 +175,18 @@
 ---------------------------------------------------------------------------
 --  Profiling code: Records how many threads were created
 
-countingThreads :: Bool 
+countingThreads :: Bool
 countingThreads = False          -- set to enable reporting or not
 
-threadCount :: TVar Integer                            
-threadCount = unsafePerformIO $ newTVar 0            
+threadCount :: TVar Integer
+threadCount = unsafePerformIO $ newTVar 0
 
 incrementThreadCount :: IO ()
-incrementThreadCount = modifyTVar_ threadCount (+1)       
+incrementThreadCount = modifyTVar_ threadCount (+1)
 
 printThreadReport :: IO ()
 printThreadReport = do
-    n <- readTVar threadCount          
-    putStrLn "----------------------------"      
-    putStrLn (show n ++ " HIO threads were forked")   
+    n <- readTVar threadCount
+    putStrLn "----------------------------"
+    putStrLn (show n ++ " HIO threads were forked")
 
diff --git a/src/Orc/Combinators.hs b/src/Orc/Combinators.hs
--- a/src/Orc/Combinators.hs
+++ b/src/Orc/Combinators.hs
@@ -100,7 +100,7 @@
 ---------------------------------------------------------------------------
 
 -- | Wait for a period of w seconds, then continue processing.
-delay :: (RealFrac a) => a -> Orc ()
+delay :: (RealFrac a, Show a) => a -> Orc ()
 delay w =  (liftIO $ threadDelay (round (w * 1000000)))
        <|> (silent $ do
              guard (w>100)
@@ -137,7 +137,7 @@
 scan f s p = do
   accum <- newTVar s
   x <- p
-  (w,w') <- modifyTVar accum (f x)
+  (_w,w') <- modifyTVar accum (f x)
   return w'
 
 -- | A variant of '<+>', pronounced or-else, which performs and returns
diff --git a/src/Orc/Monad.hs b/src/Orc/Monad.hs
--- a/src/Orc/Monad.hs
+++ b/src/Orc/Monad.hs
@@ -95,7 +95,7 @@
 runOrc p = runHIO (p # \_ -> return ())
 
 instance Applicative Orc where
-  pure  = return
+  pure    = return
   f <*> x = ap f x
 
 instance MonadPlus Orc where
@@ -147,7 +147,7 @@
 
 -- | An alternate mechanism for 'eagerly', it fires up a thread for @p@
 -- and returns a lazy thunk that contains the single (trimmed) result
--- of the computation.  Be careful to use this function with 'public'
+-- of the computation.  Be careful to use this function with 'publish'
 -- when these lazy values need to be fully evaluated before proceeding
 -- further.  For example, the following code succeeds immediately:
 --