diff --git a/Shorewall/Perl/Shorewall/Raw.pm b/Shorewall/Perl/Shorewall/Raw.pm
index 35932c756..af70825f1 100644
--- a/Shorewall/Perl/Shorewall/Raw.pm
+++ b/Shorewall/Perl/Shorewall/Raw.pm
@@ -76,6 +76,7 @@ sub process_notrack_rule( $$$$$$$ ) {
 
 	    if ( $option eq 'helper' ) {
 		fatal_error "Invalid helper' ($args)" if $args =~ /,/;
+		fatal_error "A protocol protocol is required in CT:helper rules" if $proto eq '-'; 
 		validate_helper( $args, $proto );
 		$action = "CT --helper $args";
 		$exception_rule = do_proto( $proto, '-', '-' );