Custom field in invoice badly handles Czech characters

I use version 1.5.5. Czech native characters in invoice custom field are replaced by ? during saving the invoice. Any idea how to fix it?

Best regars
Pozda

Custom tables in MySQL database is created with default charset latin1. It should be utf-8.
Following SQL commands, correct this problem.

ALTER TABLE ip_invoice_custom CONVERT TO CHARACTER SET utf8;
ALTER TABLE ip_client_custom CONVERT TO CHARACTER SET utf8;
ALTER TABLE ip_payment_custom CONVERT TO CHARACTER SET utf8;
ALTER TABLE ip_quote_custom CONVERT TO CHARACTER SET utf8;
ALTER TABLE ip_user_custom CONVERT TO CHARACTER SET utf8;

I invite @Kovah to this topic to not miss it for the next release.

Thanks for your help!