Feel free to break out the scissors or your fingernails: The Federal Trade Commission has declared that the tags and labels that some companies affix to their products to warn consumers that using third-party parts will void the warranty are, in fact, illegal.

NPR and Ars Technica report that the FTC’s Bureau of Consumer Protection has stated that these types of provisions harm both consumers and small businesses, which offer competing products and services. Per NPR:

“Specifically, the agency explained, those provisions violate the 1975 Magnuson-Moss Warranty Act, which bars companies from conditioning their warranties on demands that consumers use certain articles or services in connection with the original product.”

While many companies are already aware of this, the practice continues. The agency has sent warning letters to six major companies, which Ars called out, like Hyundai, Nintendo and Sony. For example:

“Sony’s warranty states that ‘this warranty does not apply if this product … has had the warranty seal on the PS4™ system altered, defaced, and removed.’”

No more says the FTC, which has given these six companies 30 days to correct warranty-voiding violations on their respective websites. If there’s still no change, “law enforcement action” may follow.