Tennis players will not be able to plead ignorance if they test positive for banned substances, says the International Tennis Federation.
Ex-world number one Maria Sharapova had a two-year ban for testing positive for meldonium cut to 15 months on appeal.
Meldonium was added to the banned list for 2016 but a factor in Sharapova's favour was there was no specific warning to its change in status.
The ITF believes "appropriate steps were taken to publicise any changes".
But, in a statement, it added: "Nonetheless, we have reviewed, and will continue to review, our processes for communicating changes to the prohibited list to players with the aim of ensuring that no player can claim that they had not been fully informed.