In this paper we demonstrate how error-correcting addition and multiplication can be performed using selfchecking modules. Our technique is based on the observation that a suitably designed full adder under the presence of any single stuck-at fault produces the fault-free complement of the desired output when fed by the complement of its functional input. We initially apply conventional paritybased error detection in arithmetic modules; upon detection of a fault, this is followed by input inversion, recomputation, and suitable output inversion. We present adder, register and multiplier designs that can be used in this context. We also design a large-scale circuit using this technique (an elliptical filter), outlining the area savings with respect to traditional triple modular redundancy.