diff --git a/Control/Concurrent/Lifted.hs b/Control/Concurrent/Lifted.hs
--- a/Control/Concurrent/Lifted.hs
+++ b/Control/Concurrent/Lifted.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE UnicodeSyntax, NoImplicitPrelude, FlexibleContexts, RankNTypes #-}
+{-# LANGUAGE CPP, UnicodeSyntax, NoImplicitPrelude, FlexibleContexts, RankNTypes #-}
 
 {- |
 Module      :  Control.Concurrent.Lifted
@@ -19,15 +19,19 @@
       -- * Basic concurrency operations
     , myThreadId
     , fork
+#if MIN_VERSION_base(4,4,0)
     , forkWithUnmask
+#endif
     , killThread
     , throwTo
 
+#if MIN_VERSION_base(4,4,0)
       -- ** Threads with affinity
     , forkOn
     , forkOnWithUnmask
     , getNumCapabilities
     , threadCapability
+#endif
 
       -- * Scheduling
     , yield
@@ -65,7 +69,6 @@
 import Data.Bool          ( Bool )
 import Data.Int           ( Int )
 import Data.Function      ( ($) )
-import Control.Monad      ( void )
 import System.IO          ( IO )
 import System.Posix.Types ( Fd )
 import Control.Exception  ( Exception )
@@ -80,13 +83,19 @@
 import Control.Monad.Base ( MonadBase, liftBase )
 
 -- from monad-control:
-import Control.Monad.Trans.Control
-    ( MonadBaseControl, liftBaseWith, liftBaseOp_, liftBaseDiscard )
+import Control.Monad.Trans.Control ( MonadBaseControl, liftBaseOp_, liftBaseDiscard )
 
+#if MIN_VERSION_base(4,4,0)
+import Control.Monad.Trans.Control ( liftBaseWith )
+import Control.Monad               ( void )
+#endif
+
 -- from lifted-base (this package):
 import Control.Concurrent.MVar.Lifted
 
+#include "inlinable.h"
 
+
 --------------------------------------------------------------------------------
 -- Control.Concurrent
 --------------------------------------------------------------------------------
@@ -105,6 +114,7 @@
 fork = liftBaseDiscard C.forkIO
 {-# INLINABLE fork #-}
 
+#if MIN_VERSION_base(4,4,0)
 -- | Generalized version of 'C.forkIOWithUnmask'.
 --
 -- Note that, while the forked computation @m ()@ has access to the captured
@@ -115,6 +125,7 @@
                      C.forkIOWithUnmask $ \unmask →
                        void $ runInIO $ f $ liftBaseOp_ unmask
 {-# INLINABLE  forkWithUnmask #-}
+#endif
 
 -- | Generalized version of 'C.killThread'.
 killThread ∷ MonadBase IO m ⇒ ThreadId → m ()
@@ -126,6 +137,7 @@
 throwTo tid e = liftBase $ C.throwTo tid e
 {-# INLINABLE throwTo #-}
 
+#if MIN_VERSION_base(4,4,0)
 -- | Generalized version of 'C.forkOn'.
 --
 -- Note that, while the forked computation @m ()@ has access to the captured
@@ -155,6 +167,7 @@
 threadCapability ∷ MonadBase IO m ⇒ ThreadId → m (Int, Bool)
 threadCapability = liftBase ∘ C.threadCapability
 {-# INLINABLE threadCapability #-}
+#endif
 
 -- | Generalized version of 'C.yield'.
 yield ∷ MonadBase IO m ⇒ m ()
diff --git a/Control/Concurrent/MVar/Lifted.hs b/Control/Concurrent/MVar/Lifted.hs
--- a/Control/Concurrent/MVar/Lifted.hs
+++ b/Control/Concurrent/MVar/Lifted.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE UnicodeSyntax, NoImplicitPrelude, FlexibleContexts #-}
+{-# LANGUAGE CPP, UnicodeSyntax, NoImplicitPrelude, FlexibleContexts #-}
 
 {- |
 Module      :  Control.Concurrent.MVar.Lifted
@@ -43,6 +43,10 @@
 import           Control.Concurrent.MVar  ( MVar )
 import qualified Control.Concurrent.MVar as MVar
 
+#if __GLASGOW_HASKELL__ < 700
+import Control.Monad ( (>>=), (>>), fail )
+#endif
+
 -- from base-unicode-symbols:
 import Data.Function.Unicode ( (∘) )
 
@@ -53,8 +57,15 @@
 import Control.Monad.Trans.Control ( MonadBaseControl, liftBaseOp, liftBaseDiscard )
 
 -- from lifted-base (this package):
-import Control.Exception.Lifted ( mask, onException )
+import Control.Exception.Lifted ( onException
+#if MIN_VERSION_base(4,3,0)
+                                , mask
+#else
+                                , block, unblock
+#endif
+                                )
 
+#include "inlinable.h"
 
 --------------------------------------------------------------------------------
 -- * MVars
@@ -112,19 +123,34 @@
 
 -- | Generalized version of 'MVar.modifyMVar_'.
 modifyMVar_ ∷ (MonadBaseControl IO m, MonadBase IO m) ⇒ MVar α → (α → m α) → m ()
+
+-- | Generalized version of 'MVar.modifyMVar'.
+modifyMVar ∷ (MonadBaseControl IO m, MonadBase IO m) ⇒ MVar α → (α → m (α, β)) → m β
+
+#if MIN_VERSION_base(4,3,0)
 modifyMVar_ mv f = mask $ \restore → do
                      x  ← takeMVar mv
                      x' ← restore (f x) `onException` putMVar mv x
                      putMVar mv x'
-{-# INLINABLE modifyMVar_ #-}
 
--- | Generalized version of 'MVar.modifyMVar'.
-modifyMVar ∷ (MonadBaseControl IO m, MonadBase IO m) ⇒ MVar α → (α → m (α, β)) → m β
 modifyMVar mv f = mask $ \restore → do
                     x       ← takeMVar mv
                     (x', y) ← restore (f x) `onException` putMVar mv x
                     putMVar mv x'
                     return y
+#else
+modifyMVar_ mv f = block $ do
+                     x  ← takeMVar mv
+                     x' ← unblock (f x) `onException` putMVar mv x
+                     putMVar mv x'
+
+modifyMVar mv f = block $ do
+                    x       ← takeMVar mv
+                    (x', y) ← unblock (f x) `onException` putMVar mv x
+                    putMVar mv x'
+                    return y
+#endif
+{-# INLINABLE modifyMVar_ #-}
 {-# INLINABLE modifyMVar #-}
 
 -- | Generalized version of 'MVar.addMVarFinalizer'.
diff --git a/Control/Exception/Lifted.hs b/Control/Exception/Lifted.hs
--- a/Control/Exception/Lifted.hs
+++ b/Control/Exception/Lifted.hs
@@ -74,10 +74,7 @@
 import Data.Maybe      ( Maybe )
 import Control.Monad   ( Monad, (>>=), return, liftM )
 import System.IO.Error ( IOError )
-
-#if MIN_VERSION_base(4,3,0) || defined (__HADDOCK__)
 import System.IO       ( IO )
-#endif
 
 #if __GLASGOW_HASKELL__ < 700
 import Control.Monad   ( fail )
@@ -123,6 +120,7 @@
 import Control.Monad.Trans.Control ( liftBaseOp )
 #endif
 
+#include "inlinable.h"
 
 --------------------------------------------------------------------------------
 -- * Throwing exceptions
diff --git a/System/Timeout/Lifted.hs b/System/Timeout/Lifted.hs
--- a/System/Timeout/Lifted.hs
+++ b/System/Timeout/Lifted.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE UnicodeSyntax, NoImplicitPrelude, FlexibleContexts #-}
+{-# LANGUAGE CPP, UnicodeSyntax, NoImplicitPrelude, FlexibleContexts #-}
 
 -------------------------------------------------------------------------------
 -- |
@@ -29,6 +29,8 @@
 
 -- from monad-control:
 import Control.Monad.Trans.Control ( MonadBaseControl, restoreM, liftBaseWith )
+
+#include "inlinable.h"
 
 -- | Generalized version of 'T.timeout'.
 --
diff --git a/include/inlinable.h b/include/inlinable.h
new file mode 100644
--- /dev/null
+++ b/include/inlinable.h
@@ -0,0 +1,3 @@
+#if __GLASCOW_HASKELL__ < 700
+#define INLINABLE INLINE 
+#endif
diff --git a/lifted-base.cabal b/lifted-base.cabal
--- a/lifted-base.cabal
+++ b/lifted-base.cabal
@@ -1,5 +1,5 @@
 Name:                lifted-base
-Version:             0.1
+Version:             0.1.0.1
 Synopsis:            lifted IO operations from the base library
 License:             BSD3
 License-file:        LICENSE
@@ -26,6 +26,8 @@
 -- TODO: Remove when http://hackage.haskell.org/trac/hackage/ticket/792 is fixed:
 extra-source-files:  test.hs
 
+extra-source-files: include/inlinable.h
+
 --------------------------------------------------------------------------------
 
 source-repository head
@@ -45,6 +47,9 @@
                , transformers-base    >= 0.4   && < 0.5
                , monad-control        >= 0.3   && < 0.4
 
+  Include-dirs: include
+  Includes:     inlinable.h
+
   Ghc-options: -Wall
 
 --------------------------------------------------------------------------------
@@ -53,8 +58,6 @@
   type:    exitcode-stdio-1.0
   main-is: test.hs
 
-  ghc-options: -Wall
-
   build-depends: base                 >= 3     && < 4.5
                , base-unicode-symbols >= 0.1.1 && < 0.3
                , transformers         >= 0.2   && < 0.3
@@ -63,5 +66,10 @@
                , HUnit                >= 1.2.2 && < 1.3
                , test-framework       >= 0.2.4 && < 0.5
                , test-framework-hunit >= 0.2.4 && < 0.3
+
+  Include-dirs: include
+  Includes:     inlinable.h
+
+  ghc-options: -Wall
 
 --------------------------------------------------------------------------------