In further modelling investigations of kimberlite ascent, we have discovered a minor source of error in the computer code related to gas partitioning. The depth at which mixed-gases begin to exsolve from the ascending magma was previously overestimated. The total pressure and its depth of exsolution is determined by the saturation condition using the solubility laws for each gas and then adding the partial pressures together. Re-running the code for CO2a??H2O mixtures we found that in all model runs using the same parameters and assumptions, the calculated eruption temperatures were slightly hotter and the calculated phenocryst contents were slightly decreased. The differences arise because the exsolution of volatiles in the revised calculations starts at slightly shallower depths and so there is less cooling as a consequence. These changes make no difference to the overall conclusions of the paper. Online supplementary material is available presenting the relevant corrected figures.