diff --git a/tempest/config.py b/tempest/config.py
index fc5dab8..63d4824 100644
--- a/tempest/config.py
+++ b/tempest/config.py
@@ -923,8 +923,8 @@
                     "connect_method=floating."),
     cfg.StrOpt('ssh_key_type',
                default='ecdsa',
-               help='Type of key to use for ssh connections. '
-                    'Valid types are rsa, ecdsa'),
+               choices=['ecdsa', 'rsa'],
+               help='Type of key to use for ssh connections.'),
     cfg.FloatOpt('allowed_network_downtime',
                  default=5.0,
                  help="Allowed VM network connection downtime during live "