diff --git a/sets.cabal b/sets.cabal
--- a/sets.cabal
+++ b/sets.cabal
@@ -1,5 +1,5 @@
 Name:                   sets
-Version:                0.0.2
+Version:                0.0.2.1
 Author:                 Athan Clark <athan.clark@gmail.com>
 Maintainer:             Athan Clark <athan.clark@gmail.com>
 License:                MIT
diff --git a/src/Data/Set/Class.hs b/src/Data/Set/Class.hs
--- a/src/Data/Set/Class.hs
+++ b/src/Data/Set/Class.hs
@@ -16,6 +16,7 @@
   ( HasUnion (..)
   , HasDifference (..)
   , HasIntersection (..)
+  , HasXUnion (..)
   , HasComplement (..)
   , HasSingleton (..)
   , HasSingletonWith (..)