Failed to debug with utf8 chars

Database and tables are utf8 compatible, and there are record different on master and slave, and it contains utf8 chars. (sample master: "Árvíztűrő tükörfúrógép", slave: "arvizturo tukorfurogep")

If i run pt-table-sync with --charset utf8 parameters, and debug is enabled (PTDEBUG=1), perl stop with following error:
# ChangeHandler:3580 18123 Fetching data on dbh DBI::db=HASH(0x1a55970) for REPLACE : SELECT `id`, `mezo1`, `mezo2` FROM `table` WHERE `id`='987918' LIMIT 1
# ChangeHandler:3432 18123 Wide character in print at /usr/bin/pt-table-sync line 3690. while doing table on 1.2.3.4

My quick fix: setup stderr to utf8 compatible, i put this to the pt-table-sync begin:

use utf8;
binmode(STDERR, ":utf8");