Getting powerline symbols to work in urxvt on Gentoo

I have Terminess Powerline installed and set as urxvt's font (using xfd), but the powerline symbols only show up as boxes. I've tried a few different USE flags, but it doesn't seem to be working.

In Arch, I have rxvt-unicode-patched, which I think fixes the problem. I know I've gotten powerline symbols to work in Gentoo before, but it was broken by an update.

EDIT: The wiki says to disable the alt-font-width USE flag and locally enable the vanilla USE flag. I'll look into that. emerge -pv rxvt-unicode shows vanilla and -alt-font-width but after reinstalling and a reboot still does not work.