diff --git a/src/drivers/boards/px4fmuv2/px4fmu_internal.h b/src/drivers/boards/px4fmuv2/px4fmu_internal.h
index dce51bcda2..76aa042f64 100644
--- a/src/drivers/boards/px4fmuv2/px4fmu_internal.h
+++ b/src/drivers/boards/px4fmuv2/px4fmu_internal.h
@@ -59,7 +59,7 @@ __BEGIN_DECLS
 /* Configuration ************************************************************************************/
 
 /* PX4IO connection configuration */
-#define PX4IO_SERIAL_DEVICE	"/dev/ttyS5"
+#define PX4IO_SERIAL_DEVICE	"/dev/ttyS4"
 #define PX4IO_SERIAL_TX_GPIO	GPIO_USART6_TX
 #define PX4IO_SERIAL_RX_GPIO	GPIO_USART6_RX
 #define PX4IO_SERIAL_BASE	STM32_USART6_BASE	/* hardwired on the board */