How to remove files hidden under /tmp mountpoint?

I recently created a RAM /tmp by adding this to /etc/fstab:

tmpfs /tmp tmpfs rw,nosuid,nodev,noatime   0    0 

Everything works fine, and in theory the system runs faster now, but at boot time /var/log/syslog gets:

… tmp.mount: Directory /tmp to mount over is not empty, mounting anyway. 

This situation seems inevitable, as there is never an opportunity to remove files from the filesystem version of /tmp.

The wasted space is trivial, but as a matter of interest, is there any easy way to clean out the junk hidden under the /tmp mountpoint?