Brief note on Ashtekar-Magnon-Das conserved quantities in quadratic curvature theories

In this note, we correct a mistake in the mass formula in [N. Okuyama and J. i. Koga, Phys. Rev. D 71, 084009 (2005).] which generalizes the Ashtekar-Magnon-Das method to incorporate extended gravities with quadratic curvature terms. The corrected mass formula confirms that the black hole masses for recently discovered critical gravities vanish.