diff --git a/uncloud/oneshot/main.py b/uncloud/oneshot/main.py
index 4e92a5c..dbb3b32 100644
--- a/uncloud/oneshot/main.py
+++ b/uncloud/oneshot/main.py
@@ -15,7 +15,7 @@ arg_parser = argparse.ArgumentParser('oneshot', add_help=False)
 # Actions.
 arg_parser.add_argument('--list', action='store_true',
         help='list UUID and name of running VMs')
-arg_parser.add_argument('--start', nargs=3,
+arg_parser.add_argument('--start', nargs=4,
         metavar=('NAME', 'IMAGE', 'UPSTREAM_INTERFACE', 'NETWORK'),
         help='start a VM using the OS IMAGE (full path), configuring networking on NETWORK IPv6 prefix')
 arg_parser.add_argument('--stop', metavar='UUID',