diff --git a/src/drivers/boards/auav-x21/board_config.h b/src/drivers/boards/auav-x21/board_config.h
index ccb5811c85..b10fd7ff8d 100644
--- a/src/drivers/boards/auav-x21/board_config.h
+++ b/src/drivers/boards/auav-x21/board_config.h
@@ -53,6 +53,7 @@
 /* Configuration ************************************************************************************/
 
 /* PX4IO connection configuration */
+#define BOARD_USES_PX4IO_VERSION       2
 #define PX4IO_SERIAL_DEVICE	"/dev/ttyS4"
 #define PX4IO_SERIAL_TX_GPIO	GPIO_USART6_TX
 #define PX4IO_SERIAL_RX_GPIO	GPIO_USART6_RX