diff --git a/Shorewall/Perl/Shorewall/Config.pm b/Shorewall/Perl/Shorewall/Config.pm
index 985a03c7b..b69f425d6 100644
--- a/Shorewall/Perl/Shorewall/Config.pm
+++ b/Shorewall/Perl/Shorewall/Config.pm
@@ -3106,7 +3106,8 @@ sub get_configuration( $ ) {
 #
 sub propagateconfig() {
     for my $option ( @propagateconfig ) {
-	my $value = $config{$option} || '';
+	my $value = $config{$option};
+	$value = '' unless defined $value;
 	emit "$option=\"$value\"";
     }
 }