diff --git a/instack_undercloud/undercloud.py b/instack_undercloud/undercloud.py
index e69566b63..37976e07c 100644
--- a/instack_undercloud/undercloud.py
+++ b/instack_undercloud/undercloud.py
@@ -204,12 +204,12 @@ _auth_opts = [
                      'If left unset, one will be automatically generated.')
                ),
     cfg.StrOpt('undercloud_rabbit_password',
-               default='guest',
-               help='Rabbitmq password.'
+               help=('Rabbitmq password. '
+                    'If left unset, one will be automatically generated.')
                ),
     cfg.StrOpt('undercloud_rabbit_username',
-               default='guest',
-               help='Rabbitmq username.'
+               help=('Rabbitmq username. '
+                    'If left unset, one will be automatically generated.')
                ),
     cfg.StrOpt('undercloud_heat_stack_domain_admin_password',
                help=('Heat stack domain admin password. '
diff --git a/undercloud.conf.sample b/undercloud.conf.sample
index cda2b0465..023cb2f58 100644
--- a/undercloud.conf.sample
+++ b/undercloud.conf.sample
@@ -127,11 +127,13 @@
 # (string value)
 #undercloud_rabbit_cookie = <None>
 
-# Rabbitmq password. (string value)
-#undercloud_rabbit_password = guest
+# Rabbitmq password. If left unset, one will be automatically
+# generated. (string value)
+#undercloud_rabbit_password = <None>
 
-# Rabbitmq username. (string value)
-#undercloud_rabbit_username = guest
+# Rabbitmq username. If left unset, one will be automatically
+# generated. (string value)
+#undercloud_rabbit_username = <None>
 
 # Heat stack domain admin password. If left unset, one will be
 # automatically generated. (string value)