diff -r 67b8cca2f12b -r ecde35a1af9e mercurial/hg.py
--- a/mercurial/hg.py	Mon Jul 16 16:19:53 2012 -0500
+++ b/mercurial/hg.py	Sun Jul 15 12:43:10 2012 -0400
@@ -518,7 +518,7 @@
     ui.status(_('comparing with %s\n') % util.hidepassword(dest))
     revs, checkout = addbranchrevs(repo, repo, branches, opts.get('rev'))
     if revs:
-        revs = [repo.lookup(rev) for rev in revs]
+        revs = [repo.lookup(rev) for rev in scmutil.revrange(repo, revs)]
 
     other = peer(repo, opts, dest)
     outgoing = discovery.findcommonoutgoing(repo, other, revs,