Hi, I have just noticed your post and would like to propose an alternative approach. It uses the File::Find::Rule package and simplify things (in my view). This is running on perl 5.16.0

use strict;
use warnings;
use autodie;

use File::Find::Rule;

my @f_files  = File::Find::Rule
    ->file
    ->name(qr/^f.*$/)
    ->in(qw(/dir1 /dir2 /dir3 ));

foreach (@f_files) {
    print "$_\n";
}
[download]

The output looks like:

$ perl find_f_files.pl
/dir1/f2.dat
/dir1/f.dat
/dir1/subdir1/f2.dat
/dir1/subdir1/f.dat
/dir3/subdir3/f3.dat
[download]

I hope this helps.