Source: National Restaurant Association

If your restaurant hasn’t been on the receiving end of a legal shakedown from a patent troll, your time may be running out.

Over the past few years, patent trolls—companies that purchase vague patents and threaten to sue restaurants and other businesses that don’t pay licensing fees for their use of common technologies—have cost the economy more than $20 billion a year. The number of lawsuits is on the rise. Patent Freedom, which collects data on patent troll activity, reports that 3,716 companies faced lawsuits from patent trolls in 2013, up from 3,352 the year before.