In an interview published today, Twitter CEO Jack Dorsey said conservative employees at the social media service “don’t feel safe to express their opinions” at work.

Dorsey was speaking with New York University journalism professor Jay Rosen in an interview published Friday on Recode.

Twitter has been a target lately of conservative ire for its alleged practice of shadow banning unpopular opinions, thereby making them invisible to the vast majority of users. They’ve also kicked a number of prominent conservatives off the service.

“I think it’s more and more important to at least clarify what our own bias leans towards, and just express it,” Dorsey said in the interview.

Dorsey testified before a congressional committee earlier this month about the service’s practices. His interview remarks arrives as US Attorney General Jeff Sessions said he was considering whether to investigate the services for suppressing conservative viewpoints.