diff --git a/keyring/cli.py b/keyring/cli.py
index 57b23b53..e4a4c78f 100755
--- a/keyring/cli.py
+++ b/keyring/cli.py
@@ -37,7 +37,7 @@ def __init__(self):
         )
         self.parser.add_argument(
             'operation',
-            help="get|set|del",
+            choices=["get", "set", "del"],
             nargs="?",
         )
         self.parser.add_argument(