open my $out, \my $buffer
                    or die "Couldn't patch AnyEvent::DNS; your Perl does not support in-memory filehandles";
                while (<$in>) {
                    s/sub\s+DOMAIN_PORT\b/sub DOMAIN_PORT () { 1053 } 
+sub FORMER_DOMAIN_PORT/;
                    $buffer .=  $_;
                }
                return $out;