XF 2.3 thread slugs (URLs) do not generate correctly for non-English languages

[namwooo]

I'm building non-English website and thread slugs url do not generate correctly,

For example,
I'm expecting http://localhost/index.php?threads/추석.1/ while it shows http://localhost/index.php?threads/chot-tkul.1/

is there an option to enable unicode URLs?