diff --git a/libraries/AP_HAL/AP_HAL_Boards.h b/libraries/AP_HAL/AP_HAL_Boards.h
index 4eeb739885..32a8d1592b 100644
--- a/libraries/AP_HAL/AP_HAL_Boards.h
+++ b/libraries/AP_HAL/AP_HAL_Boards.h
@@ -52,7 +52,7 @@
 */
 #define HAL_BOARD_SUBTYPE_CHIBIOS_SKYVIPER_F412	5000
 #define HAL_BOARD_SUBTYPE_CHIBIOS_FMUV3         5001
-#define HAL_BOARD_SUBTYPE_CHIBIOS_FMUV4         5002
+// #define HAL_BOARD_SUBTYPE_CHIBIOS_FMUV4         5002
 #define HAL_BOARD_SUBTYPE_CHIBIOS_GENERIC       5009
 #define HAL_BOARD_SUBTYPE_CHIBIOS_FMUV5         5013
 #define HAL_BOARD_SUBTYPE_CHIBIOS_VRBRAIN_V51   5016