A recent comment by Bader suggests that a 'fundamental error' was made in our simplified derivation of the variational nature of the quantum theory of atoms in molecules [A. Martin Pendas ,M.A. Blanco, E. Francisco, Chem. Phys. Lett. 417 (2006) 16]. However, he misinterprets our arguments in several ways, drawing conclusions that do not follow from our original Letter. (c) 2006 Elsevier B.V. All rights reserved.