Chinese ride-hailing giant Didi Chuxing will begin trialing a feature on October 18 that will allow passengers and drivers to blacklist each other, marking the latest in a series of upgrades to its security features.

The blacklisting function (in Chinese) will be accessible when canceling an order, as well as through the driver evaluation and complaints pages. Should one party decide to block the other, the driver and passenger will not be matched for 12 months.

Didi says that once an individual has been put onto a blacklist during the trial period, they cannot be removed.

The company has faced increased scrutiny following the murders of two women using the company’s Hitch service this year, as well as a string of sexual assaults. The latest incident, which occurred in August, was met with outrage online. Didi users began posting photos of themselves deleting the company’s smartphone app. It also resulted in increased downloads of apps that facilitate video calls to police.

China’s Ministry of Transportation published a commentary censuring Didi for its failure to offer effective preventive measures as well as urgent help during the incident, saying the company only tried to solve the problem with pricy settlements. The company was also summoned by authorities in ten cities around the country, which required it to implement or improve safety features.

Didi originally included an emergency button, itinerary sharing, and trip recording feature in July 2016. Since then, the company has enhanced its emergency button by making it more accessible and allowing users to instantly call the police. The company also added mandatory safety knowledge tests for drivers and more stringent facial recognition tests.

However, Didi was criticized by state media in September for advertising its in-app panic button as being “one click to call the police,” when the feature requires at least two taps. At the time, the company responded to TechNode, saying: “We are exploring ways to tackle external constraints and have the trip information sent to police automatically through partnerships with law enforcement agencies.”