Use uuid with your usb stick

mount the device somehwere

mount /dev/sdc /mnt/test

find the uuid:

ls -lF /dev/disk/by-uuid

check the mount data

vi /etc/mtab

create an entry in fstab, here you will need the UUID and the line from mtab

vi /etc/fstab

example:

 UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx /mnt/extra       ext4    errors=remount-ro 0       1