Nonlinear CMOS image sensor (CIS) technology is capable of high/wide dynamic range imaging at high frame rates without motion artifacts. However, unlike with linear CIS technology, there is no generic method for colour correction of nonlinear CIS technology. Instead, there are specific methods for specific nonlinear responses, e.g., the logarithmic response, that are based on legacy models. Inspired by recent work on generic methods for fixed pattern noise and photometric correction of nonlinear sensors, which depend only on a reasonable assumption of monotonicity, this paper proposes and validates a generic method for colour correction of nonlinear sensors. The method is composed of a nonlinear colour correction, which employs cubic Hermite splines, followed by a linear colour correction. Calibration with a colour chart is required to estimate the relevant parameters. The proposed method is validated, through simulation, using a combination of experimental data, from a monochromatic logarithmic CIS, and spectral data, reported in the literature, of actual colour filter arrays and target colour patches.