Code with suggested modifications seems does not work I expected. Another suggestion or advice?

update: fixed code to be correctly working with unicode keys

#!/usr/bin/perl_parallel -w
# For Emacs: -*- mode:cperl; mode:folding; coding:utf-8; -*-

use strict;
use utf8;
use DB_File;
use MLDBM qw (DB_File Storable);         # ) 
use Fcntl;

my $dbfile = 'database.utf';
my %data = ();

# remove old file to be sure we have only new data
unlink $dbfile if -f $dbfile;

tie ( %data, 'MLDBM', $dbfile, O_CREAT | O_RDWR, 0666, $DB_BTREE ) || 
+die $!;

# try to handle unicode by transforming to octets and back
(tied %data)->filter_store_key( sub { $_ = encode('utf8', $_); } );
(tied %data)->filter_fetch_key( sub { $_ = decode('utf8', $_); } );

open DATA, '<:utf8', 'input.utf8' or die $!;
while (<DATA>) {
  chomp;
  my ($key, $value) = split(':', $_, 2);
  $data{$key} = $value;
}
close DATA;

# now we can obtain keys as unicode strings and no only octets
print join(', ', keys %data), "\n";

untie %data;

exit 0;
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