diff --git a/perl-xCAT/xCAT/Usage.pm b/perl-xCAT/xCAT/Usage.pm
index 0aa22b952..8b03b86df 100644
--- a/perl-xCAT/xCAT/Usage.pm
+++ b/perl-xCAT/xCAT/Usage.pm
@@ -112,7 +112,7 @@ my %usage = (
        getmacs [-h|--help|-v|--version]
    PPC specific:
        getmacs <noderange> [-F filter] 
-       getmacs <noderange> [-f][-d][-D [-S server] [-G gateway] [-C client]]",
+       getmacs <noderange> [-f][-d] [arp] | [-D [-S server] [-G gateway] [-C client]]",
     "mkvm" => 
 "Usage:
     Common: