diff --git a/subcmds/checkout.py b/subcmds/checkout.py
index 51ac483..c8a09a8 100644
--- a/subcmds/checkout.py
+++ b/subcmds/checkout.py
@@ -34,10 +34,11 @@
   repo forall [<project>...] -c git checkout <branchname>
 """
 
-  def Execute(self, opt, args):
+  def ValidateOptions(self, opt, args):
     if not args:
       self.Usage()
 
+  def Execute(self, opt, args):
     nb = args[0]
     err = []
     success = []