The hypothesis c = h = G = 1 implies that unit mass is not a single-valued function but rather has two widely varying values, such as 7.4 × 10-51 kg and 4.0 × 1035 kg. Hence, the considerable body of work in theoretical physics that uses this common convention must be deemed suspect. In order to avoid this problem, theoreticians must limit themselves to c = h = 1 or, exclusively, c = G = 1 depending upon whether they are chiefly concerned with atomic physics or with gravity, respectively.