High-resolution Raman measurements of the A 1 longitudinal optical (LO) phonon in GaN were performed. The studies showed a strong evidence that the observed discrepancies between time- and frequency-domain Raman measurements of the A 1 LO phonon were due to the angular dispersion of the mode's frequency. The scattered wave vector direction in the Raman experiment fell within a solid angle that was determined by the collection optics. The true anharmonic broadening was extracted and its value was found to be in agreement with time-domain experiments.