diff --git a/Shorewall/Perl/Shorewall/Nat.pm b/Shorewall/Perl/Shorewall/Nat.pm
index ccbcfcd96..12599df68 100644
--- a/Shorewall/Perl/Shorewall/Nat.pm
+++ b/Shorewall/Perl/Shorewall/Nat.pm
@@ -269,7 +269,7 @@ sub process_one_masq1( $$$$$$$$$$ )
 				#
 				my $ports;
 
-				if ( $addr =~ s/:([^]]+)$// ) {
+				if ( $addr =~ s/:([^]:]+)$// ) {
 				    $ports = $1;
 				}