  We report the discovery of a very low-mass companion to HIP 45314 (HR 3672)
located about 2.7 arcsec north-west of HR 3672 A. With four years of epoch
difference between the two observations obtained with the Very Large Telescope
we can reject by more than 4 sigma that B would be a non-moving background
object unrelated to A. HR 3672 A is a B 7-8 main sequence star with an age of
140 \pm 80 Myr and from the magnitude difference between HR 3672 A and B and
the 2MASS magnitudes, we can estimate the magnitude of HR 3672 B (K_{s}=12.42
\pm 0.28 mag) and then, for age and distance of the primary star, using models,
its luminosity and mass (0.2-0.5 M_sun). We present a reanalysis of the
probable membership of HR 3672 A to the Platais 9 cluster, and introduce a new
method for astrometric calibration of data without dedicated calibration
images. In the deepest available image (co-add of all epochs) no additional
companion candidates within 13 arcsec were detected down to 0.03 M_sun.
