diff --git a/Crypto/Random.hs b/Crypto/Random.hs
--- a/Crypto/Random.hs
+++ b/Crypto/Random.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE ScopedTypeVariables, MonoLocalBinds, FlexibleInstances #-}
+{-# LANGUAGE ScopedTypeVariables, MonoLocalBinds, FlexibleInstances,CPP #-}
 {-|
  Maintainer: Thomas.DuBuisson@gmail.com
  Stability: beta
@@ -43,11 +43,12 @@
 	| NotEnoughEntropy	-- ^ For instantiating new generators (or reseeding)
   deriving (Eq, Ord, Show)
 
+#if !MIN_VERSION_base(4,3,0)
 instance Monad (Either GenError) where
         return = Right
-        fail   = Left . GenErrorOther
         (Left x) >>= _  = Left x
         (Right x) >>= f = f x
+#endif
 
 -- |A class of random bit generators that allows for the possibility of failure,
 -- reseeding, providing entropy at the same time as requesting bytes
diff --git a/System/Crypto/Random.hs b/System/Crypto/Random.hs
--- a/System/Crypto/Random.hs
+++ b/System/Crypto/Random.hs
@@ -22,7 +22,7 @@
 import Data.ByteString.Lazy as L
 import Crypto.Types
 
-#if defined(_WIN32) || defined (mingw32_HOST_OS) || defined(cygwin32_HOST_OS)
+#if defined(isWindows)
 {- C example for windows rng - taken from a blog, can't recall which one but thank you!
         #include <Windows.h>
         #include <Wincrypt.h>
diff --git a/crypto-api.cabal b/crypto-api.cabal
--- a/crypto-api.cabal
+++ b/crypto-api.cabal
@@ -1,5 +1,5 @@
 name:           crypto-api
-version:        0.1.1.0
+version:        0.1.2.0
 license:        BSD3
 license-file:   LICENSE
 copyright:      Thomas DuBuisson <thomas.dubuisson@gmail.com>, Dominic Steinitz (see Data.LargeWord module)
@@ -55,6 +55,8 @@
   ghc-options:   -O2
   hs-source-dirs:
   exposed-modules: Crypto.Classes, Crypto.Types, Crypto.HMAC, Data.LargeWord, Crypto.Modes, System.Crypto.Random, Crypto.Random, Crypto.Padding
+  if os(windows)
+    CC-Options: -DisWindows
   if flag(tests)
     exposed-modules: Test.Crypto, Test.AES, Test.SHA, Test.HMAC, Test.ParseNistKATs, Test.TwoFish
     build-depends: QuickCheck >= 2.3 && < 2.4, directory >= 1.0.1.0 && < 1.1