diff --git a/daphne/cli.py b/daphne/cli.py
index adea81a..715ef14 100755
--- a/daphne/cli.py
+++ b/daphne/cli.py
@@ -7,6 +7,7 @@ from .access import AccessLogGenerator
 from .endpoints import build_endpoint_description_strings
 from .server import Server
 from .utils import import_by_path
+from argparse import ArgumentError, Namespace
 
 logger = logging.getLogger(__name__)