Owing to the highly supercritical nature of hydrogen in hydrogen-hydrocarbon systems, it is difficult to accurately predict, or even correlate, the phase behavior of such mixtures with cubic equations of state and conventional mixing rules, especially as the critical point of the mixture is approached. Here we show that an extended Peng-Robinson equation of state and the recently introduced Wong-Sandler mixing rule can correlate these systems successfully, and more importantly that the mixing rule parameters can be generalized in terms of temperature and acentric factor of the hydrocarbon so that quite acceptable extrapolations and predictions are possible.