diff --git a/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h b/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
index c905e6896d..60c2cf9963 100644
--- a/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
+++ b/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
@@ -27,7 +27,7 @@ public:
         AC_AttitudeControl(ahrs, aparm, motors,
                            p_angle_roll, p_angle_pitch, p_angle_yaw,
                            pid_rate_roll, pid_rate_pitch, pid_rate_yaw),
-        _passthrough_roll(0), _passthrough_pitch(0),
+        _passthrough_roll(0), _passthrough_pitch(0), _passthrough_yaw(0),
         pitch_feedforward_filter(AC_ATTITUDE_HELI_RATE_RP_FF_FILTER),
         roll_feedforward_filter(AC_ATTITUDE_HELI_RATE_RP_FF_FILTER),
         yaw_velocity_feedforward_filter(AC_ATTITUDE_HELI_RATE_Y_VFF_FILTER),