Employees voice their concerns in the hope that leaders will change their behavior. But how do employees evaluate these changes? In the present research, we highlight the rate of behavior change as a key factor in determining leader evaluations: Leaders are seen as less authentic when they change rapidly in response to employee voice because people believe that true change takes time. We investigate this claim with three studies that adopt a mixed-method approach (n= 3,056). In Study 1, PhD students describe rapid improvement in their advisor’s behavior as less authentic than gradual improvement—even when these changes are desired. In Study 2, we employ a stimulus sampling design to test the robustness of this effect. Followers see rapid improvement as less authentic than gradual improvement across a wide array of leader behaviors. In Study 3, we highlight change difficulty as a moderator and subsequent voice as a downstream consequence: When change is hard, rapid improvement elicits a greater authenticity penalty, which undermines followers’ willingness to voice their concerns in the future.