diff --git a/control/cli.py b/control/cli.py
index 0dae08e55..e9e086b0c 100644
--- a/control/cli.py
+++ b/control/cli.py
@@ -160,7 +160,7 @@ def connect(self, host, port, client_key, client_cert, server_cert):
                  "--block-size",
                  help="Block size",
                  type=int,
-                 default=4096),
+                 default=512),
     ])
     def create_bdev(self, args):
         """Creates a bdev from an RBD image."""