diff --git a/snmp_standard/mode/memory.pm b/snmp_standard/mode/memory.pm
index ceee8d22a..456f7f16e 100644
--- a/snmp_standard/mode/memory.pm
+++ b/snmp_standard/mode/memory.pm
@@ -147,7 +147,7 @@ sub new {
     bless $self, $class;
 
     $options{options}->add_options(arguments => { 
-        'units:s'            => { name => 'units', default => '' },
+        'units:s'            => { name => 'units', default => '%' },
         'free'               => { name => 'free' },
         'swap'               => { name => 'check_swap' },
         'patch-redhat'       => { name => 'patch_redhat' },