diff --git a/powerline/commands/main.py b/powerline/commands/main.py
index 7a4751dc..df61f0d9 100644
--- a/powerline/commands/main.py
+++ b/powerline/commands/main.py
@@ -71,7 +71,7 @@ def get_argparser(ArgumentParser=argparse.ArgumentParser):
 		     '(usually `shell\' or `tmux\').'
 	)
 	parser.add_argument(
-		'side', nargs='?', choices=('left', 'right', 'above', 'aboveleft'),
+		'side', nargs=1, choices=('left', 'right', 'above', 'aboveleft'),
 		help='Side: `left\' and `right\' represent left and right side '
 		     'respectively, `above\' emits lines that are supposed to be printed '
 		     'just above the prompt and `aboveleft\' is like concatenating '