diff --git a/plugins/snmp/snmp__screenos b/plugins/snmp/snmp__screenos
index fa97ef51..643d18ff 100755
--- a/plugins/snmp/snmp__screenos
+++ b/plugins/snmp/snmp__screenos
@@ -57,15 +57,15 @@ use Munin::Plugin::SNMP;
 # This corresponds to NETSCREEN-SMI::netscreenResource
 my $oidBase = '1.3.6.1.4.1.3224.16';
 
-my $oidCpuAvg = $oidBase . '.1.1';
-my $oidCpuLast1Min = $oidBase . '.1.2';
-my $oidCpuLast5Min = $oidBase . '.1.3';
-my $oidCpuLast15Min = $oidBase . '.1.4';
-my $oidMemAllocate = $oidBase . '.2.1';
-my $oidMemLeft = $oidBase . '.2.2';
-my $oidSessAllocate = $oidBase . '.3.2';
-my $oidSessMaximum = $oidBase . '.3.3';
-my $oidSessFailed = $oidBase . '.3.4';
+my $oidCpuAvg       = "$oidBase.1.1";
+my $oidCpuLast1Min  = "$oidBase.1.2";
+my $oidCpuLast5Min  = "$oidBase.1.3";
+my $oidCpuLast15Min = "$oidBase.1.4";
+my $oidMemAllocate  = "$oidBase.2.1";
+my $oidMemLeft      = "$oidBase.2.2";
+my $oidSessAllocate = "$oidBase.3.2";
+my $oidSessMaximum  = "$oidBase.3.3";
+my $oidSessFailed   = "$oidBase.3.4";
 
 if (defined $ARGV[0] and $ARGV[0] eq "snmpconf") {
     print "require $oidBase.[23].[13].0";