The photon-drag experiment of Gibson et al. [Proc. R. Soc. London, Ser. A 370, 303 (1980)], operating in the millimeter region, is analyzed and compared with predictions following from the electromagnetic energy-momentum tensors of Minkowski, of Abraham, of Peierls, and of Einstein and Laub. In agreement with the experimentalists, it is found that the Minkowski tensor explains the observations in a straightforward way. However, it is pointed out that the other alternatives explain the observations also. The present experiment is therefore, like most of the other high-frequency experiments, unable to discriminate between the tensors.