diff --git a/Data/PrimitiveArray.hs b/Data/PrimitiveArray.hs
--- a/Data/PrimitiveArray.hs
+++ b/Data/PrimitiveArray.hs
@@ -54,6 +54,7 @@
 
 (!) :: (PrimArrayOps a b) => PrimArray a b -> a -> b
 (!) pa idx = assert (checkBounds pa idx) $ unsafeIndex pa idx
+{-# INLINE (!) #-}
 
 -- | Create a new array from an old one, mapping a function over all values.
 
diff --git a/Data/PrimitiveArray/Ix.hs b/Data/PrimitiveArray/Ix.hs
--- a/Data/PrimitiveArray/Ix.hs
+++ b/Data/PrimitiveArray/Ix.hs
@@ -4,11 +4,6 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 
 -- | PrimitiveArray with 'Ix' keys.
---
--- NOTE GHC 6.12.3 (and earlier, I guess) does not produce optimal code.
--- Current head (6.13) produces very nice code. For example, 'unsafeIndex' for
--- 2-dim. tables with lower bound (0,0) produces one multiplication, one
--- addition, one lookup, all using machine Int's.
 
 module Data.PrimitiveArray.Ix where
 
@@ -24,7 +19,7 @@
 
 
 instance (Bounded a, A.Ix a, Prim b) => PrimArrayOps a b where
-  data PrimArray a b = PaIxP {-# UNPACK #-} !a {-# UNPACK #-} !a {-# UNPACK #-} !ByteArray
+  data PrimArray a b = PaIxP !a !a {-# UNPACK #-} !ByteArray
   unsafeIndex (PaIxP lb ub arr) i = indexByteArray arr (A.unsafeIndex (lb,ub) i)
   assocs (pa@(PaIxP lb ub _)) = [(i, unsafeIndex pa i) | i<-A.range(lb,ub) ]
   fromAssocs l u z xs = runST $ do
@@ -45,7 +40,7 @@
   {-# INLINE toList #-}
 
 instance (Bounded a, A.Ix a, Prim b) => PrimArrayOpsM a b (ST s) where
-  data PrimArrayM a b (ST s) = PaIxPM {-# UNPACK #-} !a {-# UNPACK #-} !a {-# UNPACK #-} !(MutableByteArray s)
+  data PrimArrayM a b (ST s) = PaIxPM !a !a {-# UNPACK #-} !(MutableByteArray s)
   readM (PaIxPM lb ub marr) i = readByteArray marr (A.unsafeIndex (lb,ub) i)
   writeM (PaIxPM lb ub marr) i val = writeByteArray marr (A.unsafeIndex (lb,ub) i) val
   boundsM (PaIxPM lb ub _) = return (lb,ub)
@@ -71,11 +66,3 @@
   {-# INLINE fromListM #-}
   {-# INLINE toListM #-}
 
-
-
-{-
-test :: PrimArray (Int,Int) Int
-test = fromList (1,1) (5,5) [ (i*6+j) | i<-[1..5], j<-[1..5] ]
-
-testS = " " ++ show test ++ " " -- show (test,test)
--}
diff --git a/PrimitiveArray.cabal b/PrimitiveArray.cabal
--- a/PrimitiveArray.cabal
+++ b/PrimitiveArray.cabal
@@ -1,5 +1,5 @@
 Name:           PrimitiveArray
-Version:        0.0.3.1
+Version:        0.0.4.0
 License:        BSD3
 License-file:   LICENSE
 Author:         Christian Hoener zu Siederdissen
@@ -16,7 +16,7 @@
 Description:
                 Provides unboxed multidimensional tables with a small
                 interface. Comes with an instance for Ix keys. Read and Show
-                instances are provides for serialization.
+                instances are provided for serialization.
 
 extra-source-files:
   Benchmarks/Index.hs
@@ -28,7 +28,7 @@
     Data.PrimitiveArray.Internal
   Build-depends:
     base >= 4 && <5,
-    primitive >= 0.3 && < 0.4
+    primitive >= 0.4.0.1 && < 0.5
   ghc-options:
     -O2