diff --git a/libraries/AP_Motors/AP_MotorsTri.cpp b/libraries/AP_Motors/AP_MotorsTri.cpp
index 690edfd333..efdbe2cb4f 100644
--- a/libraries/AP_Motors/AP_MotorsTri.cpp
+++ b/libraries/AP_Motors/AP_MotorsTri.cpp
@@ -129,8 +129,7 @@ uint16_t AP_MotorsTri::get_motor_mask()
     // tri copter uses channels 1,2,4 and 7
     uint16_t motor_mask = (1U << AP_MOTORS_MOT_1) |
                           (1U << AP_MOTORS_MOT_2) |
-                          (1U << AP_MOTORS_MOT_4) |
-                          (1U << AP_MOTORS_CH_TRI_YAW);
+                          (1U << AP_MOTORS_MOT_4);
     uint16_t mask = motor_mask_to_srv_channel_mask(motor_mask);
 
     // add parent's mask