In one embodiment, a device in a network receives a plurality of packets from one or more neighbors of the device. Each of the packets has a scheduled delivery time interval according to a deterministic communication schedule. The device determines an amount of clock drift for each of the one or more neighbors of the device by comparing arrival times of the received packets to their scheduled delivery time intervals according to the deterministic communication schedule. The device calculates a clock adjustment based on the amount of clock drift for each of the one or more neighbors. The device adjusts a clock of the device using the calculated clock adjustment.