BED file strand '.' is produces strand -1 instead of 0?

[cmdcolin]

The BED file spec says that strand given as '.' is unstranded but when parsed I am seeing that it is -1

test.pl

use Bio::FeatureIO;
use Data::Dumper;

my $io = Bio::FeatureIO->new(
    -format => 'bed',
    -file => 'test.txt'
);

while ( my $f = $io->next_feature() ) {
    print $f->strand;
}

test.txt

NbV1Ch01	18776453	18777002	MACS2_peak_1486	34	.	2.35549	5.48617	3.42439	437