diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -4034,7 +4034,7 @@
             brev = None
 
             if checkout:
-                checkout = "%d" % repo.changelog.rev(checkout)
+                checkout = repo.changelog.rev(checkout)
 
                 # order below depends on implementation of
                 # hg.addbranchrevs(). opts['bookmark'] is ignored,