  We study a puzzle raised recently regarding the running coupling prescription
used in the calculation of forward particle production in proton-nucleus
collisions at next-to-leading order: using a coordinate space prescription
which is consistent with the one used in the high energy evolution of the
target leads to results which can be two orders of magnitude larger than the
ones obtained with a momentum space prescription. We show that this is an
artefact of the Fourier transform involved when passing between coordinate and
momentum space and propose a new coordinate space prescription which avoids
this problem.
