  We respond to the paper by De Marchi, Paresce, Straniero and Moroni (2003) on
the white dwarf cooling age of M4. The authors question the data analysis and
interpretation that led to the conclusions in Hansen et al. (2002). In their
paper, De Marchi et al. are unable to obtain photometry as deep as ours from
the same data set and therefore assert that only a lower limit to the white
dwarf cooling age for this cluster of approximately 9 Gyr can be obtained.
  In this short contribution we show that shortcomings in the data analysis and
reduction techniques of De Marchi et al. are responsible for their inability to
reach the photometry limits that our study reports. In a forthcoming paper in
which the complete techniques for age determination with white dwarfs are laid
out, we demonstrate that their method of fitting the luminosity function gives
a spuriously low white dwarf cooling age.
