A recently reported criterion [Singh V. (2010). Modified criterion for global asymptotic stability of fixed-point state-space digital filters using two's complement arithmetic. Automatica, 46,475-478], which is a modified version of an earlier criterion due to Mills-Mullis-Roberts, for the global asymptotic stability of fixed-point state-space digital filters with two's complement arithmetic is reviewed. Pertaining to second-order digital filters, it is shown that Singh's approach will never lead to a larger overflow stability region in the parameter space as compared to that obtainable via Mills-Mullis-Roberts criterion. (C) 2010 Elsevier Ltd. All rights reserved.