diff --git a/manifests/commands/definition_rules.pp b/manifests/commands/definition_rules.pp
index ae7e39e..541d48c 100644
--- a/manifests/commands/definition_rules.pp
+++ b/manifests/commands/definition_rules.pp
@@ -74,7 +74,7 @@ class confdroid_nrpe::commands::definition_rules (
     confdroid_nrpe::commands::definitions { 'check_fail2ban':
       ne_check_name    => 'check_fail2ban',
       ne_check_cmd     => 'check_procs',
-      ne_cmd_argstring => '-c $ARG1$ -a $ARG2$',
+      ne_cmd_argstring => '-c $ARG1$ -C $ARG2$',
     }
     confdroid_nrpe::commands::definitions { 'check_alloy':
       ne_check_name    => 'check_alloy',