In this paper we propose a simple method that modifies the mathematical structure of behavioral memristor models by inducing a voltage dependency in the window functions which are normally expressed as solely state dependent. This empirical method is based on the assumption that the resistive states of analog memristor devices saturate at well-defined resistive levels under constant bias voltage application, which is supported by corresponding experimental data extracted from a wide range of analog memristor devices. As the vast majority of the simplified models published to date are constructed to fit hysteretic current-voltage characteristics of practical devices, the proposed transformation is applied to render empirical models more suitable for memristor-based analog applications where the memristor resistance is configured multiple times.