The guardians of time have spoken, and this year June 30 will be one second longer. A so-called leap second will be added to the world's clock at the end of June.

The decision to plug in an additional second at the beginning of summer was announced this week by the Paris-based International Earth Rotation and Reference Systems Service (IERS), the organization tasked with maintaining global time.

News of the additional second was delivered via a memo addressed: "To authorities responsible for the measurement and distribution of time."

The reason for the extra second: the planet's rotation is slowing. The planet's clocks have had an extra second inserted, either at the end of December or June, 25 times since the practice first began in 1972. This year's leap second will be the 26th.

"They add an extra second to something called UTC (Coordinated Universal Time) in order to make sure the rate of UTC is the same as atomic time," Nick Stamatakos, the chief of Earth Orientation Parameters at the U.S. Naval Observatory, told The Telegraph.

That could be a problem for the long list of Internet-based companies, programs and services that modern society has come to rely on so heavily. In 2012, the last time a leap second was added, the inserted second threw off a variety of systems synched with UTC clocks. Mozilla, Reddit, Foursquare, Yelp, LinkedIn and StumbleUpon all crashed as a result of 2012's leap second.

Google was one of the few who avoided the glitch, having built in a preparedness technology called Leap Smear, which inserted milliseconds in their systems' clocks in anticipation of the full-second leap. It's expected more companies will employ similar measures as this year's leap second approaches.