Labaton Sucharow, the Government Accountability Project and more than 250 other whistleblower advocates are pushing the U.S. Securities and Exchange Commission to improve its program that was created four years ago as part of Dodd-Frank’s efforts to help workers report corporate wrongdoing.

The SEC whistleblower program is under threat from retaliation against tipsters, the whistleblower advocates wrote in a letter to SEC Chairwoman Mary Jo White on Friday. The agency should make whistleblower protections stronger and clearer, hold field hearings on workplace retaliation, and establish a committee that provides advice on tipsters’ reporting and protection, they wrote.