No evidence for [O III] variability in Mrk 142

Using archival data from the 2008 Lick AGN Monitoring Project, Zhang & Feng claimed to find evidence for flux variations in the narrow [O III] emission of the Seyfert 1 galaxy Mrk 142 over a two-month time span. If correct, this would imply a surprisingly compact size for the narrow-line region.We show that the claimed [O III] variations are merely the result of random errors in the overall flux calibration of the spectra. The data do not provide any support for the hypothesis that the [OIII] flux was variable during the 2008 monitoring period.