diff --git a/oslo_messaging/_drivers/amqp1_driver/opts.py b/oslo_messaging/_drivers/amqp1_driver/opts.py
index 4451c8e73..e7cc38494 100644
--- a/oslo_messaging/_drivers/amqp1_driver/opts.py
+++ b/oslo_messaging/_drivers/amqp1_driver/opts.py
@@ -191,7 +191,6 @@ amqp1_opts = [
                " consumers."),
 
     cfg.StrOpt('default_notification_exchange',
-               default=None,
                help="Exchange name used in notification addresses.\n"
                "Exchange name resolution precedence:\n"
                "Target.exchange if set\n"
@@ -200,7 +199,6 @@ amqp1_opts = [
                "else 'notify'"),
 
     cfg.StrOpt('default_rpc_exchange',
-               default=None,
                help="Exchange name used in RPC addresses.\n"
                "Exchange name resolution precedence:\n"
                "Target.exchange if set\n"