In Reference 1, Johnson and MacKinnon consider two convection schemes. For ease of reference, call these QUICK(l/8) and QUICK( 1/6). The authors state that the QUICK(1/8) scheme is only O(h2) accurate when used (as originally intended*) as a finite-volume method, and that the alternative QUICK(1/6) scheme is O(h3) in a finite-volume formulation. In fact, exactly the reverse is true: the QUICK(1/8) scheme is O ( h 3 ) accurate in a finite-volume formulation, but only O(hz) accurate in a single-point (finite-difference) formulation; whereas the QUICK (1/6) scheme is O(h3) accurate in the single-point formulation, but only O(h2) when used as a finite-volume method. This can easily be shown in two separate ways: (i) truncation-error analysis, and (ii) gridconvergence using exact diffusive fluxes.