Setting the umask in sudoers

[John P Speno]

I'm having trouble setting the umask in my sudoers file. I'm using this
syntax:

Defaults        !set_logname, syslog=auth, umask=0777

And visudo tells me:

visudo: value '0777' is invalid for option 'umask'

The man page seems to indicate that this should work.

I'm using sudo 1.6.3p5 on Tru64 UNIX 5.0A.

Todd? Anyone? Thanks!