diff --git a/src/Data/Int/Int24.hs b/src/Data/Int/Int24.hs
--- a/src/Data/Int/Int24.hs
+++ b/src/Data/Int/Int24.hs
@@ -51,11 +51,13 @@
 -- fill the uppermost bits with 1s.  Otherwise clear them to 0s.
 narrow24Int# :: Int# -> Int#
 narrow24Int# x# = if (x'# `and#` mask#) `eqWord#` mask#
-  then word2Int# ( x'# `or#` int2Word# 0xFF800000# )
-  else word2Int# ( x'# `and#` (int2Word# 0xFFFFFF#))
+  then word2Int# ( x'# `or#` int2Word# m1# )
+  else word2Int# ( x'# `and#` (int2Word# m2#))
   where
-    !x'# = int2Word# x#
+    !x'#   = int2Word# x#
     !mask# = int2Word# 0x00800000#
+    !(I# m1#) = -8388608
+    !(I# m2#) = 16777215
 
 instance Show Int24 where
     showsPrec p x = showsPrec p (fromIntegral x :: Int)
diff --git a/tests/QCUtils.hs b/tests/QCUtils.hs
--- a/tests/QCUtils.hs
+++ b/tests/QCUtils.hs
@@ -24,31 +24,3 @@
 
 instance CoArbitrary Word24 where
   coarbitrary = coarbitraryIntegral
-
-instance Arbitrary Int16 where
-  arbitrary = arbitraryBoundedIntegral
-  shrink = shrinkIntegral
-
-instance CoArbitrary Int16 where
-  coarbitrary = coarbitraryIntegral
-
-instance Arbitrary Word8 where
-  arbitrary = arbitraryBoundedIntegral
-  shrink = shrinkIntegral
-
-instance CoArbitrary Word8 where
-  coarbitrary = coarbitraryIntegral
-
-instance Arbitrary Word16 where
-  arbitrary = arbitraryBoundedIntegral
-  shrink = shrinkIntegral
-
-instance CoArbitrary Word16 where
-  coarbitrary = coarbitraryIntegral
-
-instance Arbitrary Word32 where
-  arbitrary = arbitraryBoundedIntegral
-  shrink = shrinkIntegral
-
-instance CoArbitrary Word32 where
-  coarbitrary = coarbitraryIntegral
diff --git a/word24.cabal b/word24.cabal
--- a/word24.cabal
+++ b/word24.cabal
@@ -1,5 +1,5 @@
 name:		word24
-version:        0.1.4
+version:        1.0.0
 synopsis:       24-bit word and int types for GHC
 description:	24-bit Word and Int data types.
 category:       Data
@@ -7,8 +7,8 @@
 maintainer:	John W. Lato, jwlato@gmail.com
 license:	BSD3
 license-file:	LICENSE
-homepage:       http://inmachina.net/~jwlato/haskell/word24
-tested-with:    GHC == 6.12.1, GHC == 6.10.4
+homepage:       http://www.tiresiaspress.us/haskell/word24
+tested-with:    GHC == 6.12.3, GHC == 7.0.3
 stability:	experimental
 
 cabal-version:  >= 1.6
@@ -72,4 +72,4 @@
 
 source-repository head
   type:     darcs
-  location: http://inmachina.net/~jwlato/haskell/word24
+  location: http://www.tiresiaspress.us/haskell/word24