Valve has updated Steam Trading to include Captcha in a bid to prevent unauthorised trades.
Malware can lead to computers to make Steam trades without users' knowledge, and Valve hopes the addition of Captcha to the confirmation process will combat this.
Captcha is a popular system websites use to help prove the user is a human being. Typically, it asks the user to input a series of characters based on an image.
It appears Valve is using Google's reCaptcha as opposed to its own system, according to Steam Database.
Valve has now switched from their own captcha to the new version of Google's reCAPTCHA. The "No CAPTCHA reCAPTCHA ". pic.twitter.com/oMIIcIh7KC— Steam Database (@SteamDB) January 10, 2015
Valve's John Cook admitted the update would cause "a bit of hassle", but insisted it was worthwhile.
"We know it's a bit of a hassle," he wrote in a post on the Steam Trading Cards group.
"And we don't like making trading harder for users, but we do expect it to significantly help customers who are tricked into downloading and running malware from losing their items."
The update was met with a mixed response, with some veteran Steam users calling for an option to turn Captcha off.
"People can spam me phishers or trojans all they want, I won't fall for it anyway," wrote one user. "Those who are 'green' to the internet, have the option to put Captcha's up."
Cook said Valve has excluded some third-party trading services from its Captcha process, so not all users will notice a change.
But this has had the knock on effect of creating a whitelist for trading services association with games such as Dota 2 and Team Fortress 2, with those not on the list left out in the cold.