Gaming and social networking platform Steam is adding CAPTCHA to its trading services to help distinguish bot activity from that of legitimate users.

On Friday, Steam developer John Cook took to the Steam community forum to inform users of the change. According to Cook, the move will help “prevent malware on users' machines [from] making trades on their behalf.”

He added that a few of the platform's third-party trading services had been excluded from the new CAPTCHA requirement so as not to disrupt their functionality.

Last month, reports surfaced that malware was spreading on Steam via malicious links sent on its chat service. In that instance, clicking the links would result in a malicious screensaver, or .SCR file, being downloaded, potentially exposing users' account credentials to theft.

In his Friday post, Cook also encouraged Steam users to submit additional suggestions on the trading process.