Speed box has both translated and untranslated message

When copying a file in "Speed" text box I can see both "Unlimited" option and "Nieograniczony" option (Polish translation for Nieograniczony word)
I am using winscp 4.3.2 build 1201 with english and polish versions installed.
I am copying using sftp transfter and english version.
When I click "Nieograniczony" message box appears saying "Nieograniczony is not a valid speed limit"