Location of MWC158 primary star (black hexagon, see text for details) in the isochrones of Bressan et al. (2012) for two scenarios: the scenario in which MWC158 is young, from yellow (0.3 Myr) to red (0.5 Myr), and old, from blue (0.1 Gyr) to cyan (0.2 Gyr). The triangles indicate the position of 6 M_⊙ as determined by Borges Fernandes et al. (2009) for the young track. For the old track, these positions are out of range of the plot. The dashed line indicates the upper limit on the absolute H magnitude of a hypothetical secondary of MWC158.