To decrease the likelihood of a false detection when detecting light from light pulses scattered by remote targets in a lidar system, a receiver in the lidar system includes a photodetector and a pulse-detection circuit having a gain circuit with a varying amount of gain over time. The gain circuit operates in a low-gain mode for a time period T1 beginning with time t0 when a light pulse is emitted to prevent the receiver from detecting return light pulses during the threshold time period T1. Upon expiration of the threshold time period T1, the gain circuit operates in a high-gain mode to begin detecting return light pulses until a subsequent light pulse is emitted.