--- a/src/topic/stack.py	Mon Mar 14 17:37:39 2016 +0000
+++ b/src/topic/stack.py	Mon Mar 14 17:48:31 2016 +0000
@@ -6,9 +6,8 @@
 from mercurial import error
 
 def _getstack(repo, topic):
-    # XXX need to exclude obsolete changesets
     # XXX need sorting
-    return repo.revs("topic(%s)", topic)
+    return repo.revs("topic(%s) - obsolete()", topic)
 
 def showstack(ui, repo, topic):
     if not topic: