Perl Untie Problem

[evtimokn]

Hi!
I have a problem with perl, which is new for me:

It says:

miniserv.pl: untie attempted while 1 inner references still exist at /opt/perl5/lib/5.8.6/IPC/Open3.pm line 204.

How can I find out which variable is still hanging?

The source hier is:

my $kid_rdr = gensym;
    my $kid_wtr = gensym;
    my $kid_err = gensym;

    xpipe $kid_rdr, $dad_wtr if !$dup_wtr;
    xpipe $dad_rdr, $kid_wtr if !$dup_rdr;
    xpipe $dad_err, $kid_err if !$dup_err && $dad_err ne $dad_rdr;

    $kidpid = $do_spawn ? -1 : xfork;
    if ($kidpid == 0) {		# Kid
	# A tie in the parent should not be allowed to cause problems.
	untie *STDIN;
	untie *STDOUT;