diff --git a/lib/kern.pm b/lib/kern.pm
index 29640e2..d698b15 100644
--- a/lib/kern.pm
+++ b/lib/kern.pm
@@ -378,8 +378,8 @@ sub kern_cgi {
 	my ($package, $config, $cgi) = @_;
 
 	my $kern = $config->{kern};
-	my @rigid = split(',', $kern->{rigid});
-	my @limit = split(',', $kern->{limit});
+	my @rigid = split(',', ($kern->{rigid} || ""));
+	my @limit = split(',', ($kern->{limit} || ""));
 	my $tf = $cgi->{tf};
 	my $colors = $cgi->{colors};
 	my $graph = $cgi->{graph};
diff --git a/lib/proc.pm b/lib/proc.pm
index 7c07f18..f13ecea 100644
--- a/lib/proc.pm
+++ b/lib/proc.pm
@@ -247,8 +247,8 @@ sub proc_cgi {
 
 	my $proc = $config->{proc};
 	my $kern = $config->{kern};
-	my @rigid = split(',', $proc->{rigid});
-	my @limit = split(',', $proc->{limit});
+	my @rigid = split(',', ($proc->{rigid} || ""));
+	my @limit = split(',', ($proc->{limit} || ""));
 	my $tf = $cgi->{tf};
 	my $colors = $cgi->{colors};
 	my $graph = $cgi->{graph};
diff --git a/lib/system.pm b/lib/system.pm
index 8fa13cb..35f7eaa 100644
--- a/lib/system.pm
+++ b/lib/system.pm
@@ -339,8 +339,8 @@ sub system_cgi {
 	my ($package, $config, $cgi) = @_;
 
 	my $system = $config->{system};
-	my @rigid = split(',', $system->{rigid});
-	my @limit = split(',', $system->{limit});
+	my @rigid = split(',', ($system->{rigid} || ""));
+	my @limit = split(',', ($system->{limit} || ""));
 	my $tf = $cgi->{tf};
 	my $colors = $cgi->{colors};
 	my $graph = $cgi->{graph};