On 31 December this year, we’re scheduled for another leap second. There are many stories about what leap seconds can do to infrastructure and applications, and rituals are built up around them. Such rituals stem from reality: leap seconds trigger poorly-tested code paths and run contrary to assumptions that system time always runs in one direction. It’s useful to be aware of how your infrastructure handles leap seconds and how NTP servers handle them, so you can plan around the event. Here, we look at some of the NTP measurements the RIPE Atlas platform took around the last leap second, and approaches for handling them.