Growing raid5 md pv

Hi.

Using LVM 1.0.8, kernel 2.4.23 and mdadm 1.4 on i386. There is a raid5 device under LVM's control that needs to have another disk added to it.

pvscan -- reading all physical volumes (this may take a while...)
pvscan -- ACTIVE PV "/dev/md0" of VG "dg" [111.75 GB / 4.31 GB free]
pvscan -- total: 1 [111.80 GB] / in use: 1 [111.80 GB] / in no VG: 0 [0]

A new disk will be added to the above /dev/md0 using mdadm --add.

What needs to be done on the LVM side for it to recognize the new size of the pv?

Any input will be appreciated.

Thanks
Avijit