For the purpose of enhancing the robustness of model-based controllers against modelling uncertainties and external disturbances, a simple robustness enhancer is proposed in this paper. By using the given robustness enhancer, compact analytical results of uncertainty reduction and robustness enhancement can be obtained. It is shown that with such a scheme, both modelling uncertainties and disturbances can be reduced, and hence the robustness of the control system can be enhanced by a given factor through the proper design of relevant components of the robustness enhancer.>