diff --git a/libraries/AP_HAL_ChibiOS/RCOutput_serial.cpp b/libraries/AP_HAL_ChibiOS/RCOutput_serial.cpp
index db7acbfd463b6c..e51c74a9950964 100644
--- a/libraries/AP_HAL_ChibiOS/RCOutput_serial.cpp
+++ b/libraries/AP_HAL_ChibiOS/RCOutput_serial.cpp
@@ -156,8 +156,8 @@ void RCOutput::update_channel_masks() {
         return;
     }
 
-#if HAL_PWM_COUNT > 0
-    for (uint8_t i=chan_offset; i<HAL_PWM_COUNT+chan_offset; i++) {
+#if NUM_SERVO_CHANNELS > 0
+    for (uint8_t i=0; i<NUM_SERVO_CHANNELS; i++) {
         switch (_dshot_esc_type) {
             case DSHOT_ESC_BLHELI:
             case DSHOT_ESC_BLHELI_S: