Startup warning " error: unrecognized mount option "remount-ro" or missing value"

[cosmos]

I've got 2.3 installed on a (non-server-quality) system. Contents of /etc/fstab:

# <file system> <mount point> <type> <options> <dump> <pass>
/dev/pve/root / ext3 errors=remount-ro 0 1
/dev/pve/data /var/lib/vz ext3 defaults 0 1
UUID=15c39e29-e687-4476-86ed-04d09436dffb /boot ext3 defaults 0 1
/dev/pve/swap none swap sw 0 0
proc /proc proc defaults 0 0
/dev/sda1 /mnt/backups ext3 defaults,remount-ro 0 1

Issue here is that at startup systems complains about the remount-ro option above. From /var/log/syslog:

Jun 11 07:31:54 server kernel: EXT3-fs (dm-0): using internal journal
Jun 11 07:31:54 server kernel: Adding 4194296k swap on /dev/mapper/pve-swap.  Priority:-1 extents:1 across:4194296k
Jun 11 07:31:54 server kernel: EXT3-fs: barriers disabled
Jun 11 07:31:54 server kernel: kjournald starting.  Commit interval 5 seconds
Jun 11 07:31:54 server kernel: EXT3-fs (dm-2): using internal journal
Jun 11 07:31:54 server kernel: EXT3-fs (dm-2): mounted filesystem with ordered data mode
Jun 11 07:31:54 server kernel: EXT3-fs: barriers disabled
Jun 11 07:31:54 server kernel: kjournald starting.  Commit interval 5 seconds
Jun 11 07:31:54 server kernel: EXT3-fs (sdb1): using internal journal
Jun 11 07:31:54 server kernel: EXT3-fs (sdb1): mounted filesystem with ordered data mode
Jun 11 07:31:54 server kernel: EXT3-fs (sda1): error: unrecognized mount option "remount-ro" or missing value

/dev/sdb is another disk added to take backups and stuff. Any idea why the system complains about remount-ro?