PIL ImageDraw.Draw.text fill attribute raise TypeError : an integer is required

I'm trying to write text on an image of a QR-Code, but I can't find a way to write in another colour than white (which is pretty useless for a QR-Code).

So here is the error page I get (I'm using Django too) :

TypeError at /pret/qrcode/

an integer is required

Request Method:     GET
Request URL:    http://127.0.0.1:8000/pret/qrcode/
Django Version:     1.6.1
Exception Type:     TypeError
Exception Value:    

an integer is required

Exception Location:     /usr/lib/python2.7/dist-packages/PIL/ImageDraw.py in _getink, line 146
Python Executable:  /usr/bin/python
Python Version:     2.7.3

Traceback:
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
  114.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/arthur/workspace/PretD/pret/views.py" in qrcodee
  160.         draw.text((0, 0),"This is a test",(255,255,0),font=font)
File "/usr/lib/python2.7/dist-packages/PIL/ImageDraw.py" in text
  256.         ink, fill = self._getink(fill)
File "/usr/lib/python2.7/dist-packages/PIL/ImageDraw.py" in _getink
  146.                 ink = self.draw.draw_ink(ink, self.mode)

Exception Type: TypeError at /pret/qrcode/
Exception Value: an integer is required

In my view I have:

    foo = qrcode.make(request.user.email)
    foo.format = "PNG"
    foo.save('pret/static/media/qrcode.png')

    font = ImageFont.truetype("pret/static/DejaVuSans.ttf", 20)

    img=Image.open("pret/static/media/qrcode.png")
    draw = ImageDraw.Draw(img)
    draw.text((0, 0),"String test",(255,255,0),font=font)
    draw = ImageDraw.Draw(img)
    del draw
    img.save('pret/static/media/qrcode.png')

with these imports:

import ImageDraw
import ImageFont
import Image

NB: Python couldn't find "PIL" when I tried to write

import PIL
from PIL import Image, ImageFond, ImageDraw

but it worked without mentioning it, I guess it's already included in Django by default. Plus, we can see in the traceback that Python does indeed look into /dist-packages/PIL

Thank you for your help.