diff --git a/subcmds/start.py b/subcmds/start.py
index 0c60d78..5d4c9c0 100644
--- a/subcmds/start.py
+++ b/subcmds/start.py
@@ -41,15 +41,16 @@
                  dest='all', action='store_true',
                  help='begin branch in all projects')
 
-  def Execute(self, opt, args):
+  def ValidateOptions(self, opt, args):
     if not args:
       self.Usage()
 
     nb = args[0]
     if not git.check_ref_format('heads/%s' % nb):
-      print("error: '%s' is not a valid name" % nb, file=sys.stderr)
-      sys.exit(1)
+      self.OptionParser.error("'%s' is not a valid name" % nb)
 
+  def Execute(self, opt, args):
+    nb = args[0]
     err = []
     projects = []
     if not opt.all: