Throws Value Error, does not patch font.

[SirFireball3521]

I ran: ./powerline-fontpatcher --source-font /usr/share/fonts/opentype/PowerlineSymbols.otf /usr/share/fonts/truetype/vlgothic/OxygenMono-Regular.ttf. All the paths in this are correct, and I have rw permissions. Here's the full error message:

Traceback (most recent call last):
  File "./powerline-fontpatcher", line 144, in <module>
    raise SystemExit(main(sys.argv[1:]))
  File "./powerline-fontpatcher", line 141, in main
    return patch_fonts(args.source_font, args.target_fonts, args.rename_font)
  File "./powerline-fontpatcher", line 133, in patch_fonts
    patch_one_font(source_font, target_font, rename_font)
  File "./powerline-fontpatcher", line 104, in patch_one_font
    target_font.selection.select(source_glyph.unicode)
ValueError: Encoding is out of range