I correct an error made by Vega et al. [Appl. Opt. 42, 4152 (2003)], who derived the spectral dispersion properties of a virtually imaged phased-array etalon using a ray-based, multibounce interference analysis. I demonstrate that the corrected dispersion law is in agreement with the results obtained by paraxial wave theory [Xiao et al., IEEE J. Quantum Electron.40, 420 (2004)].