The temperature dependence of the paramagnetic zero-field susceptibility chi is calculated for the second-neighbour S=¹/₂ Heisenberg model and for the Baxter-Wu model, from Pade approximants to existing high-temperature series expansions and by Monte Carlo simulations. The data are well represented by a power law chi T=(t')^-y using the critical susceptibility exponent gamma over the whole paramagnetic temperature range when a nonlinear scaling variable t' is used; namely t'=1-T_c/T for the second-neighbour models and t'=1-(T_c/T)² for the Baxter-Wu model.