diff --git a/libraries/AP_HAL/board/esp32.h b/libraries/AP_HAL/board/esp32.h
index ee73fca795..8d936ee7f9 100644
--- a/libraries/AP_HAL/board/esp32.h
+++ b/libraries/AP_HAL/board/esp32.h
@@ -76,6 +76,9 @@
 #define AP_COMPASS_BACKEND_DEFAULT_ENABLED 0
 #endif
 
+// we don't need 32, 16 is enough
+#define NUM_SERVO_CHANNELS 16
+
 // disble temp cal of gyros by default
 #define HAL_INS_TEMPERATURE_CAL_ENABLE 0