  Doppler-based planet surveys point to an increasing occurrence rate of giant
planets with stellar mass. Such surveys rely on evolved stars for a sample of
intermediate-mass stars (so-called retired A stars), which are more amenable to
Doppler observations than their main-sequence progenitors. However, it has been
hypothesised that the masses of subgiant and low-luminosity red-giant stars
targeted by these surveys --- typically derived from a combination of
spectroscopy and isochrone fitting --- may be systematically overestimated.
Here, we test this hypothesis for the particular case of the exoplanet-host
star HD 212771 using K2 asteroseismology. The benchmark asteroseismic mass
($1.45^{+0.10}_{-0.09}\:\text{M}_{\odot}$) is significantly higher than the
value reported in the discovery paper ($1.15\pm0.08\:\text{M}_{\odot}$), which
has been used to inform the stellar mass-planet occurrence relation. This
result, therefore, does not lend support to the above hypothesis. Implications
for the fates of planetary systems are sensitively dependent on stellar mass.
Based on the derived asteroseismic mass, we predict the post-main-sequence
evolution of the Jovian planet orbiting HD 212771 under the effects of tidal
forces and stellar mass loss.
