It is shown that the equations solved in the paper (Rosa and Ziebell 2010 Nucl. Fusion50 115009) do not describe the consistent evolution of the parallel electric field and the electron cyclotron driven current density in a geometry with a magnetic island. Therefore, do the 'effects' of the induced parallel electric field on the electron cyclotron driven current as claimed in this paper have no bearing on the stabilizing effect of electron cyclotron current drive on neoclassical tearing modes.