Using a hashref:

#!/usr/bin/perl

use strict;
use warnings; 
use Data::Dumper::Concise;;

my(%x) = (qw(1 2 3 4));
my $ref = \%x;
my $i;
for ($i = 1; $i<5; ++$i) {
    $x{$i} = 'x';
}
print Dumper($ref);
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