Valve Corporation, the developer of first-person shooter video game Counter-Strike, has issued a strong warning to any professional player that match fixing, or gambling of any kind while playing the video game should be put to a stop.

“Professional players, teams, and anyone involved in the production of CS:GO events, should under no circumstances gamble on CS:GO matches, associate with high volume CS:GO gamblers, or deliver information to others that might influence their CS:GO bets,” the company said in a statement.

As such, Valve has imposed a new set of rules that forbids professional players from placing bets on matches, even those that they’re not directly partaking in. The new rule will now be imposed on all tournaments sponsored by the company.

While it’s hard to actually police betting on Counter-Strike: Global Offensive matches, the company is pleading to its players to follow the new rule to “protect the integrity of these matches” because match fixing episodes could have a substantial impact on the heat and stability of the sport.”

“Betting using inside information, or even the perception or suspicion thereof, carries a significant risk of damaging your personal brand, your team, your community, and may lead to exclusion from future Valve-sponsored events,” the company added.

The announcement came after a recent of high-profile betting controversies, including match fixing claims, came to light. Valve even took the unprecedented step of banning some players for participating in throwing away games for the sake of winning bets.

This includes 19 players from Epsilon eSports, ex-ESC Gaming and WinneR, all of whom were banned from participating in an upcoming tournament in Poland after evidence of match fixing came to light. Five players from ex-ESC Gaming ultimately saw their bans overturned, but 14 players from the other two teams remained.