diff --git a/src/drivers/drv_gpio.h b/src/drivers/drv_gpio.h
index a54b377381..46082e9ca9 100644
--- a/src/drivers/drv_gpio.h
+++ b/src/drivers/drv_gpio.h
@@ -71,9 +71,6 @@
 /** configure the board GPIOs in (arg) as inputs */
 #define GPIO_SET_INPUT	GPIOC(2)
 
-/** configure the board GPIO (arg) for the fourth alternate function (if supported) */
-#define GPIO_SET_ALT_4	GPIOC(6)
-
 /** set the GPIOs in (arg) */
 #define GPIO_SET	GPIOC(10)
 
diff --git a/src/drivers/px4fmu/fmu.cpp b/src/drivers/px4fmu/fmu.cpp
index a1c11d2b9e..7ff8dc4007 100644
--- a/src/drivers/px4fmu/fmu.cpp
+++ b/src/drivers/px4fmu/fmu.cpp
@@ -2910,10 +2910,6 @@ PX4FMU::gpio_ioctl(struct file *filp, int cmd, unsigned long arg)
 		ret = gpio_set_function(arg, cmd);
 		break;
 
-	case GPIO_SET_ALT_4:
-		ret = -EINVAL;
-		break;
-
 	case GPIO_SET:
 	case GPIO_CLEAR:
 		ret = gpio_write(arg, cmd);