Why is my Mythbuntu install missing /sbin/mount.nfs?

I am trying to mount an NFS share on my Mythbuntu installation, but am getting this error:

mount: wrong fs type, bad option, bad superblock on
192.168.10.190:/share,
       missing codepage or helper program, or other error
       (for several filesystems (e.g. nfs, cifs) you might
       need a /sbin/mount.<type> helper program)
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

dmesg | tail yields nothing of interest, but if it does seem that I am indeed missing /sbin/mount.nfs:

ls /sbin/mount*
/sbin/mountall  /sbin/mount.cifs  /sbin/mount.fuse  /sbin/mount.lowntfs-3g  /sbin/mount.ntfs  /sbin/mount.ntfs-3g  /sbin/mount.smbfs

Why would this be missing, and what should I do to rectify?