diff --git a/storablevector.cabal b/storablevector.cabal
--- a/storablevector.cabal
+++ b/storablevector.cabal
@@ -1,5 +1,5 @@
 Name:                storablevector
-Version:             0.1
+Version:             0.1.0
 Category:            Data
 Synopsis:            Fast, packed, strict storable arrays with a list interface like ByteString
 Description:
@@ -27,5 +27,6 @@
 CPP-Options:         -DSLOW_FOREIGN_PTR
 Hs-Source-Dirs:      ., tests
 Main-Is:             tests.hs
+Other-Modules:       QuickCheckUtils
 Extensions:          CPP, ForeignFunctionInterface
 Build-Depends:       base, haskell98, bytestring, QuickCheck
diff --git a/tests/QuickCheckUtils.hs b/tests/QuickCheckUtils.hs
new file mode 100644
--- /dev/null
+++ b/tests/QuickCheckUtils.hs
@@ -0,0 +1,245 @@
+{-# OPTIONS_GHC -O -fglasgow-exts #-}
+--
+-- Uses multi-param type classes
+--
+module QuickCheckUtils where
+
+import Test.QuickCheck.Batch
+import Test.QuickCheck
+import Text.Show.Functions
+
+import Control.Monad        ( liftM2 )
+import Data.Char
+import Data.List
+import Data.Word
+import Data.Int
+import System.Random
+import System.IO
+
+import Data.ByteString.Fusion
+import qualified Data.ByteString      as P
+import qualified Data.StorableVector  as V
+
+import qualified Data.ByteString.Char8      as PC
+
+-- Enable this to get verbose test output. Including the actual tests.
+debug = False
+
+mytest :: Testable a => a -> Int -> IO ()
+mytest a n = mycheck defaultConfig
+    { configMaxTest=n
+    , configEvery= \n args -> if debug then show n ++ ":\n" ++ unlines args else [] } a
+
+mycheck :: Testable a => Config -> a -> IO ()
+mycheck config a =
+  do rnd <- newStdGen
+     mytests config (evaluate a) rnd 0 0 []
+
+mytests :: Config -> Gen Result -> StdGen -> Int -> Int -> [[String]] -> IO ()
+mytests config gen rnd0 ntest nfail stamps
+  | ntest == configMaxTest config = do done "OK," ntest stamps
+  | nfail == configMaxFail config = do done "Arguments exhausted after" ntest stamps
+  | otherwise               =
+      do putStr (configEvery config ntest (arguments result)) >> hFlush stdout
+         case ok result of
+           Nothing    ->
+             mytests config gen rnd1 ntest (nfail+1) stamps
+           Just True  ->
+             mytests config gen rnd1 (ntest+1) nfail (stamp result:stamps)
+           Just False ->
+             putStr ( "Falsifiable after "
+                   ++ show ntest
+                   ++ " tests:\n"
+                   ++ unlines (arguments result)
+                    ) >> hFlush stdout
+     where
+      result      = generate (configSize config ntest) rnd2 gen
+      (rnd1,rnd2) = split rnd0
+
+done :: String -> Int -> [[String]] -> IO ()
+done mesg ntest stamps =
+  do putStr ( mesg ++ " " ++ show ntest ++ " tests" ++ table )
+ where
+  table = display
+        . map entry
+        . reverse
+        . sort
+        . map pairLength
+        . group
+        . sort
+        . filter (not . null)
+        $ stamps
+
+  display []  = ".\n"
+  display [x] = " (" ++ x ++ ").\n"
+  display xs  = ".\n" ++ unlines (map (++ ".") xs)
+
+  pairLength xss@(xs:_) = (length xss, xs)
+  entry (n, xs)         = percentage n ntest
+                       ++ " "
+                       ++ concat (intersperse ", " xs)
+
+  percentage n m        = show ((100 * n) `div` m) ++ "%"
+
+------------------------------------------------------------------------
+
+instance Arbitrary Char where
+    arbitrary     = choose ('a', 'i')
+    coarbitrary c = variant (ord c `rem` 4)
+
+instance (Arbitrary a, Arbitrary b) => Arbitrary (PairS a b) where
+  arbitrary             = liftM2 (:*:) arbitrary arbitrary
+  coarbitrary (a :*: b) = coarbitrary a . coarbitrary b
+
+instance Arbitrary Word8 where
+    arbitrary = choose (97, 105)
+    coarbitrary c = variant (fromIntegral ((fromIntegral c) `rem` 4))
+
+instance Arbitrary Int64 where
+  arbitrary     = sized $ \n -> choose (-fromIntegral n,fromIntegral n)
+  coarbitrary n = variant (fromIntegral (if n >= 0 then 2*n else 2*(-n) + 1))
+
+instance Arbitrary a => Arbitrary (MaybeS a) where
+  arbitrary            = do a <- arbitrary ; elements [NothingS, JustS a]
+  coarbitrary NothingS = variant 0
+  coarbitrary _        = variant 1 -- ok?
+
+{-
+instance Arbitrary Char where
+  arbitrary = choose ('\0', '\255') -- since we have to test words, unlines too
+  coarbitrary c = variant (ord c `rem` 16)
+
+instance Arbitrary Word8 where
+  arbitrary = choose (minBound, maxBound)
+  coarbitrary c = variant (fromIntegral ((fromIntegral c) `rem` 16))
+-}
+
+instance Random Word8 where
+  randomR = integralRandomR
+  random = randomR (minBound,maxBound)
+
+instance Random Int64 where
+  randomR = integralRandomR
+  random  = randomR (minBound,maxBound)
+
+integralRandomR :: (Integral a, RandomGen g) => (a,a) -> g -> (a,g)
+integralRandomR  (a,b) g = case randomR (fromIntegral a :: Integer,
+                                         fromIntegral b :: Integer) g of
+                            (x,g) -> (fromIntegral x, g)
+
+instance Arbitrary V where
+    arbitrary = V.pack `fmap` arbitrary
+    coarbitrary s = coarbitrary (V.unpack s)
+
+instance Arbitrary P.ByteString where
+  arbitrary = P.pack `fmap` arbitrary
+  coarbitrary s = coarbitrary (P.unpack s)
+
+instance Functor ((->) r) where
+    fmap = (.)
+
+instance Monad ((->) r) where
+    return = const
+    f >>= k = \ r -> k (f r) r
+
+instance Functor ((,) a) where
+    fmap f (x,y) = (x, f y)
+
+------------------------------------------------------------------------
+--
+-- We're doing two forms of testing here. Firstly, model based testing.
+-- For our Lazy and strict bytestring types, we have model types:
+--
+--  i.e.    Lazy    ==   Byte
+--              \\      //
+--                 List 
+--
+-- That is, the Lazy type can be modeled by functions in both the Byte
+-- and List type. For each of the 3 models, we have a set of tests that
+-- check those types match.
+--
+-- The Model class connects a type and its model type, via a conversion
+-- function. 
+--
+--
+class Model a b where
+  model :: a -> b  -- get the abstract value from a concrete value
+
+--
+-- Connecting our Lazy and Strict types to their models. We also check
+-- the data invariant on Lazy types.
+--
+-- These instances represent the arrows in the above diagram
+--
+instance Model P [W]    where model = P.unpack
+instance Model P [Char] where model = PC.unpack
+instance Model V [W]    where model = V.unpack
+instance Model V P      where model = P.pack . V.unpack
+
+-- Types are trivially modeled by themselves
+instance Model Bool  Bool         where model = id
+instance Model Int   Int          where model = id
+instance Model Int64 Int64        where model = id
+instance Model Int64 Int          where model = fromIntegral
+instance Model Word8 Word8        where model = id
+instance Model Ordering Ordering  where model = id
+instance Model Char Char          where model = id
+
+-- More structured types are modeled recursively, using the NatTrans class from Gofer.
+class (Functor f, Functor g) => NatTrans f g where
+    eta :: f a -> g a
+
+-- The transformation of the same type is identity
+instance NatTrans [] []             where eta = id
+instance NatTrans Maybe Maybe       where eta = id
+instance NatTrans ((->) X) ((->) X) where eta = id
+instance NatTrans ((->) W) ((->) W) where eta = id
+instance NatTrans ((->) Char) ((->) Char) where eta = id
+
+-- We have a transformation of pairs, if the pairs are in Model
+instance Model f g => NatTrans ((,) f) ((,) g) where eta (f,a) = (model f, a)
+
+-- And finally, we can take any (m a) to (n b), if we can Model m n, and a b
+instance (NatTrans m n, Model a b) => Model (m a) (n b) where model x = fmap model (eta x)
+
+------------------------------------------------------------------------
+
+-- Some short hand.
+type X = Int
+type W = Word8
+type P = P.ByteString
+type V = V.Vector Word8
+
+------------------------------------------------------------------------
+--
+-- These comparison functions handle wrapping and equality.
+--
+-- A single class for these would be nice, but note that they differe in
+-- the number of arguments, and those argument types, so we'd need HList
+-- tricks. See here: http://okmij.org/ftp/Haskell/vararg-fn.lhs
+--
+
+eq1 f g = \a         ->
+    model (f a)         == g (model a)
+eq2 f g = \a b       ->
+    model (f a b)       == g (model a) (model b)
+eq3 f g = \a b c     ->
+    model (f a b c)     == g (model a) (model b) (model c)
+eq4 f g = \a b c d   ->
+    model (f a b c d)   == g (model a) (model b) (model c) (model d)
+eq5 f g = \a b c d e ->
+    model (f a b c d e) == g (model a) (model b) (model c) (model d) (model e)
+
+--
+-- And for functions that take non-null input
+--
+eqnotnull1 f g = \x     -> (not (isNull x)) ==> eq1 f g x
+eqnotnull2 f g = \x y   -> (not (isNull y)) ==> eq2 f g x y
+eqnotnull3 f g = \x y z -> (not (isNull z)) ==> eq3 f g x y z
+
+class    IsNull t            where isNull :: t -> Bool
+instance IsNull P.ByteString where isNull = P.null
+instance IsNull V            where isNull = V.null
+
+instance Show V where
+    show = show . V.unpack