diff --git a/hw-prim.cabal b/hw-prim.cabal
--- a/hw-prim.cabal
+++ b/hw-prim.cabal
@@ -1,7 +1,7 @@
 cabal-version:  2.2
 
 name:           hw-prim
-version:        0.6.2.26
+version:        0.6.2.27
 synopsis:       Primitive functions and data types
 description:    Primitive functions and data types.
 category:       Data
@@ -101,6 +101,7 @@
     HaskellWorks.Data.Vector.BoxedVectorLike
     HaskellWorks.Data.Vector.Storable
     HaskellWorks.Data.Vector.StorableVectorLike
+    HaskellWorks.Data.Word
   other-modules:      Paths_hw_prim
   autogen-modules:    Paths_hw_prim
   hs-source-dirs:     src
diff --git a/src/HaskellWorks/Data/Word.hs b/src/HaskellWorks/Data/Word.hs
new file mode 100644
--- /dev/null
+++ b/src/HaskellWorks/Data/Word.hs
@@ -0,0 +1,14 @@
+{-# LANGUAGE MagicHash #-}
+
+module HaskellWorks.Data.Word
+  ( ltWord64
+  ) where
+
+import Data.Word
+import GHC.Int
+import GHC.Prim
+import GHC.Word  hiding (ltWord64)
+
+ltWord64 :: Word64 -> Word64 -> Word64
+ltWord64 (W64# a#) (W64# b#) = fromIntegral (I64# (ltWord# a# b#))
+{-# INLINE ltWord64 #-}