The Olympics are coming, but companies who aren’t Coca-Cola, McDonald’s, Visa, or P&G, beware: if you own a company and you aren’t sponsoring the games themselves, you’d better not even think about posting on social media about them. At least not until after August 24, when the blackout period ends.

The U.S. Olympic Committee (USOC) recently sent out a letter advising companies, even those sponsoring athletes but not the Olympics themselves, on all the things that they can’t do. Like, for example, mention the Olympics or the athletes at all.

Olympic trademarks are strictly guarded. In fact, each host country is required by the International Olympic Committee to create “special trademark protection” laws to limit who can use them. In the US, those rules are dictated by US Code Chapter 2205.

Individuals, news media, and official sponsors are exempt from these rules. But non-sponsoring businesses must tread carefully if they want to make any mention of the Olympics or Olympians, especially on social media. Companies who fail to meet these rules face consequences: Athletic apparel company Oiselle, which sponsors 15 Olympic hopefuls but does not officially sponsor the Olympics, was contacted by the US Olympic Committee to remove content mentioning the Olympics from their website. Had Oiselle not taken down the content, they likely would have faced legal action.

The rules are pretty specific–and restrictive: “Do not create social media posts that are Olympic themed, that feature Olympic trademarks, that contain Games imagery, or congratulate Olympic performances unless you are an official sponsor.”

Some things businesses are required to avoid:

  • Trademarked words or phrases (Olympic, Olympian, Team USA, Olympian, etc.)
  • Anything referencing the location of the Olympics (Road to Rio, Rio 2016, etc.)
  • Hashtags using Olympic trademarks (#TeamUSA, #Rio2016, etc.)
  • Hosting any Olympic- or Paralympic-themed events for employees
  • Sharing anything from official Olympic social media accounts, including retweeting

Most businesses aren’t giving up, though. Ketchum Sports & Entertainment, as well as several marketing agencies around the country, are currently brainstorming about how best to work within the rules and still ride the wave of Olympic fever.