The error performance of generalized selection combining (GSC), which optimally combines the highest signal-to-noise ratio (SNR) signals out of total diversity signals, in Nakagamifading was recently evaluated using moment generating function (MGF) of the GSC output SNR. However, no single closed-form expression for the MGF exists for arbitrary and . In fact, closed-form expression for the MGF is possible only for individual combination of and . In this letter, a single closed-form expression for approximating the MGF is, therefore, derived and employed in evaluating the approximate error performance. Although the approximation is only applicable for GSC with being a factor of , it nonetheless achieves a high degree of accuracy.