svn and multibyte characters

I just made an svn repository of a bunch of pdfs. They are titled, and have subdirectories named after their first author.

All of this seems to have worked just fine when I uploaded the initial installment using "svn import".

However, when I use svn to add or commit files, it trips over the multibyte characters:

% svn add /
svn: Can't convert string from native encoding to 'UTF-8':

This happens even when using for example zsh compiled for multibyte support. Is this an inherent limitation of svn? Is there any workaround?