urxvt not loading xft font from ~/.Xdefaults

urxvt not loading xft font from ~/.Xdefaults

Some basic details:
archlinux 3.9.3-1
xmonad 0.11
urxvt 9.18
I can get urxvt to load my desired font manually using:
urxvt -fn "xft:Ubuntu Mono"
However, I'm unable to get this font to load through ~/.Xdefaults - Here's what I have at the moment:
Xft*dpi: 96
Xft*antialias: true
Xft*rgba: rgb
Xft*hinting: true
Xft*hintstyle: hintslight

URxvt*transparent: true
URxvt*shading: 40
URxvt*saveLines: 12000
URxvt*foreground: White
URxvt*background: Black
URxvt*scrollBar: false
Urxvt*font: xft:Ubuntu Mono
Urxvt*boldFont: xft:Ubuntu Mono
All other urxvt settings load fine, except the font. I've tried many different combinations like: xft:Ubuntu Mono:pixelsize=14:style=regular etc, but nothing seems to work.
I've tried xrdb -merge ~/.Xdefaults, xrdb -load ~/.Xdefaults, and restarting X entirely. I've also tried these settings in ~/.Xresources, however urxvt seems to ignore those settings entirely. What am I missing?