--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -199,7 +199,7 @@ def backout(ui, repo, node=None, rev=Non
     commit_opts = opts.copy()
     commit_opts['addremove'] = False
     if not commit_opts['message'] and not commit_opts['logfile']:
-        commit_opts['message'] = _("Backed out changeset %s") % (hex(node))
+        commit_opts['message'] = _("Backed out changeset %s") % (short(node))
         commit_opts['force_editor'] = True
     commit(ui, repo, **commit_opts)
     def nice(node):