The NFL said in a memo on Thursday that it is working with “state lawmakers and regulators, as well as [its] sports betting partners” to limit or outright prohibit certain types of prop bets.

The NFL categorized the prohibited prop bets as follows:

The memo comes in response to federal investigations into NBA and MLB players regarding cases of alleged gambling violations.

It also comes at a time when major sports leagues have signed lucrative deals with gambling companies following the Supreme Court’s decision to strike down the Professional and Amateur Sports Protection Act in 2018. That ruling cleared the way for individual states to determine the legality of sports gambling.

Currently, gambling on sports is allowed in 38 states, alongside Washington D.C. and Puerto Rico.