diff --git a/genvalidity.cabal b/genvalidity.cabal
--- a/genvalidity.cabal
+++ b/genvalidity.cabal
@@ -1,13 +1,13 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.31.2.
+-- This file has been generated from package.yaml by hpack version 0.33.0.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 80513e8153ba436dea2585e9c58009687ae95e2cfa57f1e8b341c3d103fd2e85
+-- hash: a5dc5e1588ff412e964237d33283651af0936a55506c5f8e6919d2ab901c77ec
 
 name:           genvalidity
-version:        0.10.0.2
+version:        0.11.0.0
 synopsis:       Testing utilities for the validity library
 description:    Note: There are companion instance packages for this library:
                 .
diff --git a/src/Data/GenValidity.hs b/src/Data/GenValidity.hs
--- a/src/Data/GenValidity.hs
+++ b/src/Data/GenValidity.hs
@@ -48,6 +48,7 @@
 {-# LANGUAGE DefaultSignatures #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MagicHash #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE MultiWayIf #-}
 {-# LANGUAGE TypeOperators #-}
@@ -103,11 +104,14 @@
 import Data.List.NonEmpty (NonEmpty((:|)))
 #endif
 #if MIN_VERSION_base(4,8,0)
-import Data.Word (Word8, Word16, Word32, Word64)
+import Data.Word (Word64)
+import GHC.Word (Word8(..), Word16(..), Word32(..), Word(..))
 #else
-import Data.Word (Word, Word8, Word16, Word32, Word64)
+import Data.Word (Word, Word64)
+import GHC.Word (Word8(..), Word16(..), Word32(..), Word(..))
 #endif
-import Data.Int (Int8, Int16, Int32, Int64)
+import Data.Int (Int64)
+import GHC.Int (Int8(..), Int16(..), Int32(..), Int(..))
 import Data.Char (chr)
 import Data.Ratio ((%))
 import GHC.Generics
@@ -591,28 +595,28 @@
     shrinkValid = shrinkUnchecked
 
 instance GenUnchecked Int8 where
-    genUnchecked = genIntX
-    shrinkUnchecked = shrink
+    genUnchecked = genUncheckedInt (I8#)
+    shrinkUnchecked = shrinkUncheckedInt (\(I# i#) -> I8# i#) (\(I8# i#) -> I# i#)
 
 instance GenValid Int8 where
-    genValid = genUnchecked
-    shrinkValid = shrinkUnchecked
+    genValid = genIntX
+    shrinkValid = shrink
 
 instance GenUnchecked Int16 where
-    genUnchecked = genIntX
-    shrinkUnchecked = shrink
+    genUnchecked = genUncheckedInt (I16#)
+    shrinkUnchecked = shrinkUncheckedInt (\(I# i#) -> I16# i#) (\(I16# i#) -> I# i#)
 
 instance GenValid Int16 where
-    genValid = genUnchecked
-    shrinkValid = shrinkUnchecked
+    genValid = genIntX
+    shrinkValid = shrink
 
 instance GenUnchecked Int32 where
-    genUnchecked = genIntX
-    shrinkUnchecked = shrink
+    genUnchecked = genUncheckedInt (I32#)
+    shrinkUnchecked = shrinkUncheckedInt (\(I# i#) -> I32# i#) (\(I32# i#) -> I# i#)
 
 instance GenValid Int32 where
-    genValid = genUnchecked
-    shrinkValid = shrinkUnchecked
+    genValid = genIntX
+    shrinkValid = shrink
 
 instance GenUnchecked Int64 where
     genUnchecked = genIntX
@@ -631,28 +635,28 @@
     shrinkValid = shrinkUnchecked
 
 instance GenUnchecked Word8 where
-    genUnchecked = genWordX
-    shrinkUnchecked = shrink
+    genUnchecked = genUncheckedWord (W8#)
+    shrinkUnchecked = shrinkUncheckedWord (\(W# w#) -> W8# w#) (\(W8# w#) -> W# w#)
 
 instance GenValid Word8 where
-    genValid = genUnchecked
-    shrinkValid = shrinkUnchecked
+    genValid = genWordX
+    shrinkValid = shrink
 
 instance GenUnchecked Word16 where
-    genUnchecked = genWordX
-    shrinkUnchecked = shrink
+    genUnchecked = genUncheckedWord (W16#)
+    shrinkUnchecked = shrinkUncheckedWord (\(W# w#) -> W16# w#) (\(W16# w#) -> W# w#)
 
 instance GenValid Word16 where
-    genValid = genUnchecked
-    shrinkValid = shrinkUnchecked
+    genValid = genWordX
+    shrinkValid = shrink
 
 instance GenUnchecked Word32 where
-    genUnchecked = genWordX
-    shrinkUnchecked = shrink
+    genUnchecked = genUncheckedWord (W32#)
+    shrinkUnchecked = shrinkUncheckedWord (\(W# w#) -> W32# w#) (\(W32# w#) -> W# w#)
 
 instance GenValid Word32 where
-    genValid = genUnchecked
-    shrinkValid = shrinkUnchecked
+    genValid = genWordX
+    shrinkValid = shrink
 
 instance GenUnchecked Word64 where
     genUnchecked = genWordX
diff --git a/src/Data/GenValidity/Utils.hs b/src/Data/GenValidity/Utils.hs
--- a/src/Data/GenValidity/Utils.hs
+++ b/src/Data/GenValidity/Utils.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE DefaultSignatures #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MagicHash #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE MultiWayIf #-}
 {-# LANGUAGE ScopedTypeVariables #-}
@@ -43,11 +44,18 @@
     , genDouble
     , genFloatX
     , genInteger
+    , genUncheckedInt
+    , shrinkUncheckedInt
+    , genUncheckedWord
+    , shrinkUncheckedWord
     ) where
 
 import Test.QuickCheck hiding (Fixed)
 import System.Random
 import GHC.Float
+import GHC.Int (Int(..))
+import GHC.Word (Word(..))
+import GHC.Exts (Word#, Int#)
 import Data.Ratio
 #if !MIN_VERSION_QuickCheck(2,8,0)
 import Data.List (sortBy)
@@ -361,3 +369,19 @@
       bi <- resize b genInteger
       ci <- resize c genIntSizedInteger
       pure $ ai * bi + ci
+
+genUncheckedInt :: (Int# -> a) -> Gen a
+genUncheckedInt func = do
+  (I# i#) <- genIntX
+  pure $ func i#
+
+shrinkUncheckedInt :: (Int -> a) -> (a -> Int) -> a -> [a]
+shrinkUncheckedInt fromInt toInt = fmap fromInt . shrink . toInt
+
+genUncheckedWord :: (Word# -> a) -> Gen a
+genUncheckedWord func = do
+  (W# w#) <- genWordX
+  pure $ func w#
+
+shrinkUncheckedWord :: (Word -> a) -> (a -> Word) -> a -> [a]
+shrinkUncheckedWord fromWord toWord = fmap fromWord . shrink . toWord