simple python 2 to python question

[Chris]

Hello all,
I'm working on a port I maintain to become py3x compatible.
I'm down to one lousy error:
passwd.py", line 25    chmod(self.pw_file, 0600)
                            ^
SyntaxError: invalid token

I tried to sort it, but failed. So allowed 2to3 to take a shot
at it, and it returned:
chmod(self.pw_file, 0o600)

which just seems wrong.

What am I missing -- aside from more familiarity with python3 ;-)

Thanks!

--Chris