Setting kernel module option permissions

I have just updated my /etc/modprobe.d/nvidia-graphics-drivers.conf file to add the line below, hoping this will set the group permissions of the devices as I expect.

...
options nvidia NVreg_DeviceFileGID=0

However, looking at /proc/driver/nvidia/params after a reboot, the group permissions are still set to a different user ID.

...
DeviceFileGID: 1003
...

What am I missing?