diff --git a/libraries/AP_Motors/AP_MotorsMatrix.cpp b/libraries/AP_Motors/AP_MotorsMatrix.cpp
index 3092bff1b9..cfacf881b8 100644
--- a/libraries/AP_Motors/AP_MotorsMatrix.cpp
+++ b/libraries/AP_Motors/AP_MotorsMatrix.cpp
@@ -43,9 +43,13 @@ void AP_MotorsMatrix::set_update_rate( uint16_t speed_hz )
     // record requested speed
     _speed_hz = speed_hz;
 
-    // we can use a mask of 0xFF here as rc_set_freq masks with actual
-    // motor mask
-    rc_set_freq(0xFF, _speed_hz );
+    uint16_t mask = 0;
+    for (uint8_t i=0; i<AP_MOTORS_MAX_NUM_MOTORS; i++) {
+        if (motor_enabled[i]) {
+            mask |= 1U << i;
+        }
+    }
+    rc_set_freq(mask, _speed_hz );
 }
 
 // set frame class (i.e. quad, hexa, heli) and type (i.e. x, plus)