Net::FTP truncating at 4096-yte boundaries

Net::FTP (libnet 1.06) running within Win32(Win98) Perl 5.005_03 is
truncating files at the last even multiple of 4096 bytes.
Code is straight forward:
$ftp = Net::FTP->new("xxx.org");
    $ftp->login("xxx","yyy");
    $ftp->cwd("/home/virtual/xxx/home/httpd/html/proof");
    $ftp->put("e:/xxx/access/development/file.htm");
    $ftp->quit;

Destination is Linux running proftpd. /var/log/xferlog shows the transfers
as multiples of 4096.

Would appreciate any tips.