diff --git a/mercurial/revset.py b/mercurial/revset.py
index c3e49b127de05e1f48ba464e40a3f82cb4d7541b_bWVyY3VyaWFsL3JldnNldC5weQ==..d4f2f2d7421049d5f3ea39c8f47a3eec3e04ffdd_bWVyY3VyaWFsL3JldnNldC5weQ== 100644
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -2692,7 +2692,7 @@
         self._cache[x] = False
         return False
 
-class spanset(object):
+class spanset(_orderedsetmixin):
     """Duck type for baseset class which represents a range of revisions and
     can work lazily and without having all the range in memory