The heat capacities were measured by adiabatic calorimetry down to 6 K on both the right-handed isomer and a racemic mixture of 4-(1-methylheptyloxy)-4'-cyanobiphenyl. A thermodynamic relationship between two crystalline phases has been established and inversion between the stable and the metastable crystals has been found for the isomer. The contradiction between a previous calorimetric study and the results of inelastic neutron scattering and infrared spectroscopy has been resolved. No crystallization was detected for the racemic mixture. The behavior around the glass transition has been analyzed.