diff --git a/intset.cabal b/intset.cabal
--- a/intset.cabal
+++ b/intset.cabal
@@ -1,5 +1,5 @@
 name:                  intset
-version:               0.1.0.0
+version:               0.1.0.1
 category:              Data
 license:               BSD3
 license-file:          LICENSE
diff --git a/src/Data/IntervalSet/Internal.hs b/src/Data/IntervalSet/Internal.hs
--- a/src/Data/IntervalSet/Internal.hs
+++ b/src/Data/IntervalSet/Internal.hs
@@ -1499,7 +1499,7 @@
       x7 = x6 .|. x6 `shiftR` 32
   in x7 `xor` (x7 `shiftR` 1)
 #else
-  in x6 `xor` (x6 `shiftRL` 1)
+  in x6 `xor` (x6 `shiftR` 1)
 #endif
 {-# INLINE highestBitMask #-}