diff --git a/Shorewall/Perl/Shorewall/IPAddrs.pm b/Shorewall/Perl/Shorewall/IPAddrs.pm
index 56f9f225d..1971e9df7 100644
--- a/Shorewall/Perl/Shorewall/IPAddrs.pm
+++ b/Shorewall/Perl/Shorewall/IPAddrs.pm
@@ -287,7 +287,12 @@ sub resolve_proto( $ ) {
     my $proto = $_[0];
     my $number;
 
-    $proto =~ /^(\d+)$/ ? $proto <= 65535 ? $proto : undef : defined( $number = $nametoproto{$proto} ) ? $number : scalar getprotobyname $proto;
+    if ( $proto =~ /^\d+$/ || $proto =~ /^0x/ ) {
+	$number = numeric_value ( $proto );
+	defined $number && $number <= 65535 ? $number : undef;
+    } else {
+	defined( $number = $nametoproto{$proto} ) ? $number : scalar getprotobyname $proto;
+    }
 }
 
 sub proto_name( $ ) {