Stochastic finite‐fault ground‐motion simulation is widely used in various scientific and engineering applications. However, the current theoretical modeling of the corner frequency used in the source spectrum model is problematic as it does not consider the impact of rupture velocity. This article provides a modification of the current corner‐frequency modeling and establishes a correlation between corner frequency and rupture velocity, making the source spectrum model more theoretically consistent. An additional inspection of the source‐duration model is provided, and the appropriateness of the application of the widely used source‐duration model is discussed. A detailed comparison between the updated corner‐frequency model and the currently used model (embodied in EXSIM) is provided for various magnitudes. For validation purposes, the updated corner‐frequency and source‐duration model is applied to predict the ground motions on rock sites during the 2012 5.4 Moe earthquake that occurred in southeastern Australia and the 2014 6.5 Ludian earthquake that occurred in southwestern China. The results show that the updated model is reliable for providing more accurate estimates of corner frequency, source duration, and ground‐motion amplitudes with smaller average residuals than the currently used model.