Corporations have a tendency to add ridiculous requirements to their terms of service to legally protect themselves from liability in case of even the least likely of scenarios–it’s just one of the many reasons so many people sign them without reading. Amazon, however, has rewarded thorough customers with a funny new clause in its expanded terms of service for Amazon Web Services, which limits its liability in the event of a zombie outbreak.

A clause in the terms for Lumberyard, Amazon’s new free video game engine, tells designers not to use the engine to make “life-critical” software, such as self-driving cars and medical equipment, though the restriction would be waived in the event of a viral outbreak triggering a undead-driven apocalypse.

“57.10 Acceptable Use; Safety-Critical Systems. Your use of the Lumberyard Materials must comply with the AWS Acceptable Use Policy. The Lumberyard Materials are not intended for use with life-critical or safety-critical systems, such as use in operation of medical equipment, automated transportation systems, autonomous vehicles, aircraft or air traffic control, nuclear facilities, manned spacecraft, or military use in connection with live combat. However, this restriction will not apply in the event of the occurrence (certified by the United States Centers for Disease Control or successor body) of a widespread viral infection transmitted via bites or contact with bodily fluids that causes human corpses to reanimate and seek to consume living human flesh, blood, brain or nerve tissue and is likely to result in the fall of organized civilization.”

Related: Try Amazon Prime Free for 30 Days

Now, I’m not a lawyer, so take this with a grain of salt, but in layman’s terms it seems like this says that designers who use Lumberyard can sue Amazon if they use the engine to build a life-saving piece of software that somehow fails, but only if zombies are real… That seems fair, right?

Announced Tuesday, Lumberyard is a free 3D game engine for making PC and console games, similar to popular platforms, such as Unity and Unreal Engine 4. At first glance, the service’s main distinguishing features are tools for expanded integration with Twitch, another Amazon’s gaming-related service. Amazon said it plans to add mobile and VR support. Amazon also announced GameLift, a service offering scalable server support for games with online multiplayer.