diff --git a/demo/Demo.hs b/demo/Demo.hs
--- a/demo/Demo.hs
+++ b/demo/Demo.hs
@@ -1,4 +1,4 @@
-module Demo where
+module Main where
 
 import qualified Data.Number.MPFR as M --import functions
 import Data.Number.MPFR.Instances.Up -- import instances
@@ -61,15 +61,14 @@
     print $ M.urandomb rsP 1000
     print $ M.urandomb rsP 1000
 
-main = do print $ s1 1000 1000
-          print $ s6 1000 1000
-          print $ e1 1000 1000
-          print $ e2 1000 1000
+main = do print $ s1 1000 100000
+          print $ s6 1000 100000
+          print $ e1 1000 100000
+          print $ e2 1000 100000
           testRandom
-          putStrLn $ "exp 1 = " ++ (M.toStringExp 10000 $ M.exp M.Up 100 one)
-          putStrLn $ "exp -1 = " ++ (M.toStringExp 10000 $ M.exp M.Up 100 (M.neg M.Up 100 one))
-          putStrLn $ "exp 1 = " ++ (M.toStringExp 10000 $ M.exp M.Up 100 one)
-          putStrLn $ "exp -1 = " ++ (M.toStringExp 10000 $ M.exp M.Up 100 (M.neg M.Up 100 one))
+          let c1 = one
+          putStrLn $ "exp 1 = " ++ (M.toStringExp 10000 $ M.exp M.Up 100 c1)
+          putStrLn $ "exp -1 = " ++ (M.toStringExp 10000 $ M.exp M.Up 100 (M.neg M.Up 100 c1))
     
 one = 1 :: M.MPFR
           
diff --git a/hmpfr.cabal b/hmpfr.cabal
--- a/hmpfr.cabal
+++ b/hmpfr.cabal
@@ -1,41 +1,57 @@
 name:                hmpfr
-version:             0.3.2
+version:             0.3.3
 synopsis:            Haskell binding to the MPFR library
 description:         Haskell binding to the MPFR library. This version is compatible
                      with MPFR 2.4.* and later and will not work with previous releases
                      of the MPFR library.
                      .
-                     /Since MPFR uses GMP, this library does not work correctly/
-                     /with a ghc that has been compiled with integer-gmp./  
-                     /When using ghc, this library will require that the ghc/
-                     /is compiled  with integer-simple./
+                     /Since MPFR uses GMP, this library features infrequent but serious errors/
+                     /with a ghc (at least <= 7.2.1) that has been compiled with integer-gmp./  
+                     /When using ghc, it is recommended to use one compiled with integer-simple./
                      .
-                     The library includes a mutable interface
-                     in addition to the pure one. These functions should have a
-                     lot less overhead than the pure ones.
+                     The library includes both a pure and a mutable interface.
+                     The mutable interface should have a lot less overhead 
+                     than the pure one.
                      .
                      Some simple examples of usage can be found in demo/Demo.hs.
 category:            Data, Math
 license:             BSD3
 license-file:        LICENSE
 Stability:           experimental
-tested-with:         GHC == 6.12.3
+tested-with:         GHC == 6.12.3, GHC == 7.2.1
 author:              Aleš Bizjak, Michal Konečný
 maintainer:          Michal Konečný <mikkonecny@gmail.com>
 Homepage:            http://code.google.com/p/hmpfr/
-
 build-type:          Simple
-cabal-version:       >= 1.2
+cabal-version:       >= 1.6
 Extra-source-files:  demo/Demo.hs
 
 Data-files:          README
                      dict.txt
                      ChangeLog
 
+source-repository head
+  type:     mercurial
+  location: https://code.google.com/p/hmpfr/
+
+source-repository this
+  type:     mercurial
+  location: https://code.google.com/p/hmpfr/
+  tag:      0.3.3
+
+
+flag use-integer-simple
+  description: Use this when compiling using a ghc that uses integer-simple instead of integer-gmp.
+  default: False
+
 Library
   build-Depends:       base > 3 && < 5
-  if impl(ghc)
+  if flag(use-integer-simple)
      build-Depends:    integer-simple
+     cpp-options: -DINTEGER_SIMPLE
+  else
+     build-Depends:    integer-gmp
+     cpp-options: -DINTEGER_GMP
 
   Other-modules:       Data.Number.MPFR.FFIhelper
                        Data.Number.MPFR.Internal
@@ -64,7 +80,7 @@
                        Data.Number.MPFR.Mutable
                        
   build-tools:         hsc2hs
-  GHC-options:         -Wall -fno-warn-orphans -O2
+  GHC-options:         -Wall -fno-warn-orphans
   GHC-prof-options:    -prof -auto
   hs-source-dirs:      src
   include-dirs:        cbits
diff --git a/src/Data/Number/MPFR/Assignment.hs b/src/Data/Number/MPFR/Assignment.hs
--- a/src/Data/Number/MPFR/Assignment.hs
+++ b/src/Data/Number/MPFR/Assignment.hs
@@ -22,12 +22,15 @@
 
 import Foreign.Storable
 
-#if (__GLASGOW_HASKELL__ >= 610) && (__GLASGOW_HASKELL__ < 612)
-#error "hmpfr can be compiled only with ghc 6.12 or newer with integer-simple" 
-#elif __GLASGOW_HASKELL__ >= 612
+#ifdef INTEGER_SIMPLE
 import GHC.Integer.Simple.Internals
 #endif
 
+#ifdef INTEGER_GMP
+--import GHC.Integer.GMP.Internals
+import GHC.Float
+#endif
+
 set     :: RoundMode -> Precision -> MPFR -> MPFR
 set r p = fst . set_ r p
 
@@ -137,15 +140,20 @@
 fromIntegerA r p = stringToMPFR r p 10 . show 
 
 bitsInInteger :: (Num a) => Integer -> a
+
+#  ifdef INTEGER_SIMPLE
 bitsInInteger Naught = 0
 bitsInInteger (Positive pos) = bitsInPositive pos
 bitsInInteger (Negative pos) = bitsInPositive pos
 bitsInPositive :: (Num a) => Positive -> a
 bitsInPositive None = 0
 bitsInPositive (Some _ rest) = 
-    sizeofInt + (bitsInPositive rest)
+    (8 * sizeofInt) + (bitsInPositive rest)
 sizeofInt :: (Num a) => a 
-sizeofInt = fromIntegral $ sizeOf (0 :: Int)
+sizeofInt = fromIntegral $ sizeOf (0 :: Int) -- in bytes
+#else
+bitsInInteger = fromIntegral . GHC.Float.integerLogBase 2
+#endif
 
 compose             :: RoundMode -> Precision -> (Integer, Int) -> MPFR 
 compose r p (i, ii) = div2i r p (fromIntegerA r p i) ii
diff --git a/src/Data/Number/MPFR/Instances/Down.hs b/src/Data/Number/MPFR/Instances/Down.hs
--- a/src/Data/Number/MPFR/Instances/Down.hs
+++ b/src/Data/Number/MPFR/Instances/Down.hs
@@ -1,4 +1,4 @@
--- {-# LANGUAGE MagicHash, CPP #-}
+{-# LANGUAGE MagicHash, CPP #-}
 {-|
     Module      :  Data.Number.MPFR.Instances.Down
     Description :  Instance declarations
@@ -31,15 +31,15 @@
 
 import Data.Ratio
 
+#ifdef INTEGER_SIMPLE
+--import GHC.Integer.Simple.Internals
+#endif
+#ifdef INTEGER_GMP
+import GHC.Integer.GMP.Internals
+import qualified GHC.Exts as E
+#endif
 
--- #if (__GLASGOW_HASKELL__ >= 610) && (__GLASGOW_HASKELL__ < 612)
--- import GHC.Integer.Internals
--- #elif __GLASGOW_HASKELL__ >= 612
--- import GHC.Integer.GMP.Internals
--- #endif
 
--- import qualified GHC.Exts as E
-
 instance Num MPFR where
     d + d'        = A.add Down (maxPrec d d') d d'
     d - d'        = A.sub Down (maxPrec d d') d d'
@@ -47,10 +47,14 @@
     negate d      = A.neg Down (getPrec d) d
     abs d         = A.absD Down (getPrec d) d
     signum        = fromInt Down minPrec . fromMaybe (-1) .sgn
+#ifdef INTEGER_SIMPLE
     fromInteger i = 
         fromIntegerA Down (max minPrec $ 1 + bitsInInteger i) i
---    fromInteger (S# i) = fromInt Down minPrec (E.I# i)
---    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
+#ifdef INTEGER_GMP
+    fromInteger (S# i) = fromInt Down minPrec (E.I# i)
+    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
 
 instance Real MPFR where
     toRational d = n % 2 ^ e
diff --git a/src/Data/Number/MPFR/Instances/Near.hs b/src/Data/Number/MPFR/Instances/Near.hs
--- a/src/Data/Number/MPFR/Instances/Near.hs
+++ b/src/Data/Number/MPFR/Instances/Near.hs
@@ -1,4 +1,4 @@
--- {-# LANGUAGE MagicHash, CPP #-}
+{-# LANGUAGE MagicHash, CPP #-}
 {-|
     Module      :  Data.Number.MPFR.Instances.Near
     Description :  Instance declarations
@@ -30,13 +30,13 @@
 
 import Data.Ratio
 
--- #if (__GLASGOW_HASKELL__ >= 610) && (__GLASGOW_HASKELL__ < 612)
--- import GHC.Integer.Internals
--- #elif __GLASGOW_HASKELL__ >= 612
--- import GHC.Integer.GMP.Internals
--- #endif
-
--- import qualified GHC.Exts as E
+#ifdef INTEGER_SIMPLE
+--import GHC.Integer.Simple.Internals
+#endif
+#ifdef INTEGER_GMP
+import GHC.Integer.GMP.Internals
+import qualified GHC.Exts as E
+#endif
 
 instance Num MPFR where
     d + d'        = A.add Near (maxPrec d d') d d'
@@ -45,10 +45,14 @@
     negate d      = A.neg Near (getPrec d) d
     abs d         = A.absD Near (getPrec d) d
     signum        = fromInt Near minPrec . fromMaybe (-1) . sgn
+#ifdef INTEGER_SIMPLE
     fromInteger i = 
         fromIntegerA Near (max minPrec $ 1 + bitsInInteger i) i
---    fromInteger (S# i) = fromInt Zero minPrec (E.I# i)
---    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
+#ifdef INTEGER_GMP
+    fromInteger (S# i) = fromInt Near minPrec (E.I# i)
+    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
 
 instance Real MPFR where
     toRational d = n % 2 ^ e
diff --git a/src/Data/Number/MPFR/Instances/Up.hs b/src/Data/Number/MPFR/Instances/Up.hs
--- a/src/Data/Number/MPFR/Instances/Up.hs
+++ b/src/Data/Number/MPFR/Instances/Up.hs
@@ -1,4 +1,4 @@
--- {-# LANGUAGE MagicHash, CPP #-}
+{-# LANGUAGE MagicHash, CPP #-}
 
 {-|
     Module      :  Data.Number.MPFR.Instances.Up
@@ -31,13 +31,14 @@
 
 import Data.Ratio
 
--- #if (__GLASGOW_HASKELL__ >= 610) && (__GLASGOW_HASKELL__ < 612)
--- import GHC.Integer.Internals
--- #elif __GLASGOW_HASKELL__ >= 612
--- import GHC.Integer.GMP.Internals
--- #endif
+#ifdef INTEGER_SIMPLE
+--import GHC.Integer.Simple.Internals
+#endif
+#ifdef INTEGER_GMP
+import GHC.Integer.GMP.Internals
+import qualified GHC.Exts as E
+#endif
 
--- import qualified GHC.Exts as E
 
 instance Num MPFR where
     d + d'        = A.add Up (maxPrec d d') d d'
@@ -46,10 +47,14 @@
     negate d      = A.neg Up (getPrec d) d
     abs d         = A.absD Up (getPrec d) d
     signum        = fromInt Up minPrec . fromMaybe (-1) . sgn
+#ifdef INTEGER_SIMPLE
     fromInteger i = 
         fromIntegerA Up (max minPrec $ 1 + bitsInInteger i) i
---    fromInteger (S# i) = fromInt Up minPrec (E.I# i)
---    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
+#ifdef INTEGER_GMP
+    fromInteger (S# i) = fromInt Up minPrec (E.I# i)
+    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
 
 instance Real MPFR where
     toRational d = n % 2 ^ e
diff --git a/src/Data/Number/MPFR/Instances/Zero.hs b/src/Data/Number/MPFR/Instances/Zero.hs
--- a/src/Data/Number/MPFR/Instances/Zero.hs
+++ b/src/Data/Number/MPFR/Instances/Zero.hs
@@ -1,4 +1,4 @@
--- {-# LANGUAGE MagicHash, CPP #-}
+{-# LANGUAGE MagicHash, CPP #-}
 {-|
     Module      :  Data.Number.MPFR.Instances.Zero
     Description :  Instance declarations
@@ -31,13 +31,13 @@
 
 import Data.Ratio
 
--- #if (__GLASGOW_HASKELL__ >= 610) && (__GLASGOW_HASKELL__ < 612)
--- import GHC.Integer.Internals
--- #elif __GLASGOW_HASKELL__ >= 612
--- import GHC.Integer.GMP.Internals
--- #endif
-
--- import qualified GHC.Exts as E
+#ifdef INTEGER_SIMPLE
+--import GHC.Integer.Simple.Internals
+#endif
+#ifdef INTEGER_GMP
+import GHC.Integer.GMP.Internals
+import qualified GHC.Exts as E
+#endif
 
 instance Num MPFR where
     d + d'        = A.add Zero (maxPrec d d') d d'
@@ -46,10 +46,14 @@
     negate d      = A.neg Zero (getPrec d) d
     abs d         = A.absD Zero (getPrec d) d
     signum        = fromInt Zero minPrec . fromMaybe (-1) . sgn
+#ifdef INTEGER_SIMPLE
     fromInteger i = 
         fromIntegerA Zero (max minPrec $ 1 + bitsInInteger i) i
---    fromInteger (S# i) = fromInt Zero minPrec (E.I# i)
---    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
+#ifdef INTEGER_GMP
+    fromInteger (S# i) = fromInt Zero minPrec (E.I# i)
+    fromInteger i@(J# n _) = fromIntegerA Zero (fromIntegral . abs $ E.I# n * bitsPerIntegerLimb) i 
+#endif
 
 instance Real MPFR where
     toRational d = n % 2 ^ e
diff --git a/src/Data/Number/MPFR/Mutable/Internal.hs b/src/Data/Number/MPFR/Mutable/Internal.hs
--- a/src/Data/Number/MPFR/Mutable/Internal.hs
+++ b/src/Data/Number/MPFR/Mutable/Internal.hs
@@ -29,7 +29,7 @@
 -- | A mutable MPFR. Currently this is just a newtype wrapped STRef to
 -- a MPFR but this may change in the future for a more efficient implementation.
 -- Type argument @s@ is the state variable argument for the @ST@ type.
-newtype MMPFR s = MMPFR { run :: STRef s MPFR }
+newtype MMPFR s = MMPFR { run :: STRef s MPFR } deriving Eq
 
 {-# INLINE unsafeWriteMMPFR #-}
 -- | Replace the state of the mutable MPFR with a new one. The actual limbs are