diff --git a/bundles/postfix/metadata.py b/bundles/postfix/metadata.py
index 1ccf633..f457b9b 100644
--- a/bundles/postfix/metadata.py
+++ b/bundles/postfix/metadata.py
@@ -14,7 +14,7 @@ defaults = {
         'postfix': {
             'services': {
                 'POSTFIX PROCESS': {
-                    'command_on_monitored_host': '/usr/local/share/icinga/plugins/check_systemd_unit postfix@-',
+                    'command_on_monitored_host': '/usr/local/share/icinga/plugins/check_systemd_unit postfix' + ('' if node.os_version >= (13,) else '@-'),
                 },
                 'POSTFIX QUEUE': {
                     'command_on_monitored_host': 'sudo /usr/local/share/icinga/plugins/check_postfix_queue -w 20 -c 40 -d 50',