We demonstrate, by ab initio calculations on more than 60 molecules, that zero-point vibrational corrections to isotropic magnetizabilities in general are negligible, being less than 0.5% for almost all molecules studied. The exceptions to this rule are aromatic and anti-aromatic ring systems where the effect may be as large as 1% due to a sizable vibrational contribution to the component of the magnetizability perpendicular to the molecular plane. For the magnetizability anisotropy, zero-point vibrational corrections are much more important, often contributing 5 - 10% of the total vibrationally averaged magnetizability anisotropy. We also demonstrate that the additivity of magnetizabilities (known as Pascal's rule) breaks down in the case of fluorine-containing molecules.