diff --git a/src/drivers/px4io/px4io.cpp b/src/drivers/px4io/px4io.cpp
index b66c4a68c7..e61f291f58 100644
--- a/src/drivers/px4io/px4io.cpp
+++ b/src/drivers/px4io/px4io.cpp
@@ -1344,6 +1344,13 @@ PX4IO::io_set_arming_state()
 
 		_armed = armed.armed;
 
+		if (armed.prearmed) {
+			set |= PX4IO_P_SETUP_ARMING_FMU_PREARMED;
+
+		} else {
+			clear |= PX4IO_P_SETUP_ARMING_FMU_PREARMED;
+		}
+
 		if ((armed.lockdown || armed.manual_lockdown) && !_lockdown_override) {
 			set |= PX4IO_P_SETUP_ARMING_LOCKDOWN;
 			_lockdown_override = true;
@@ -2284,6 +2291,7 @@ PX4IO::print_status(bool extended_status)
 	printf("arming 0x%04hx%s%s%s%s%s%s%s%s%s%s\n",
 	       arming,
 	       ((arming & PX4IO_P_SETUP_ARMING_FMU_ARMED)		? " FMU_ARMED" : " FMU_DISARMED"),
+	       ((arming & PX4IO_P_SETUP_ARMING_FMU_PREARMED)		? " FMU_PREARMED" : " FMU_NOT_PREARMED"),
 	       ((arming & PX4IO_P_SETUP_ARMING_IO_ARM_OK)		? " IO_ARM_OK" : " IO_ARM_DENIED"),
 	       ((arming & PX4IO_P_SETUP_ARMING_MANUAL_OVERRIDE_OK)	? " MANUAL_OVERRIDE_OK" : ""),
 	       ((arming & PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM)		? " FAILSAFE_CUSTOM" : ""),
diff --git a/src/modules/px4iofirmware/mixer.cpp b/src/modules/px4iofirmware/mixer.cpp
index 0a0a1ee55b..80943a7b73 100644
--- a/src/modules/px4iofirmware/mixer.cpp
+++ b/src/modules/px4iofirmware/mixer.cpp
@@ -211,9 +211,12 @@ mixer_tick(void)
 		     );
 
 	should_arm_nothrottle = (
-					(r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK)		/* IO initialised without error */
-					&& (r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF)	/* and IO is armed */
-					&& (r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK)	/* and there is valid input via or mixer */
+					(r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK)                /* IO initialised without error */
+					&& (r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF)        /* and IO is armed */
+					&& (((r_setup_arming & PX4IO_P_SETUP_ARMING_FMU_PREARMED)    /* and FMU is prearmed */
+					     && (r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK))     /* and there is valid input via or mixer */
+					    || (r_status_flags & PX4IO_P_STATUS_FLAGS_RAW_PWM)        /* or direct PWM is set */
+					   )
 				);
 
 	should_always_enable_pwm = (
diff --git a/src/modules/px4iofirmware/protocol.h b/src/modules/px4iofirmware/protocol.h
index 08092bd338..3dde775ef6 100644
--- a/src/modules/px4iofirmware/protocol.h
+++ b/src/modules/px4iofirmware/protocol.h
@@ -182,15 +182,16 @@
 #define PX4IO_P_SETUP_ARMING			1	 /* arming controls */
 #define PX4IO_P_SETUP_ARMING_IO_ARM_OK		(1 << 0) /* OK to arm the IO side */
 #define PX4IO_P_SETUP_ARMING_FMU_ARMED		(1 << 1) /* FMU is already armed */
-#define PX4IO_P_SETUP_ARMING_MANUAL_OVERRIDE_OK	(1 << 2) /* OK to switch to manual override via override RC channel */
-#define PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM	(1 << 3) /* use custom failsafe values, not 0 values of mixer */
-#define PX4IO_P_SETUP_ARMING_INAIR_RESTART_OK	(1 << 4) /* OK to try in-air restart */
-#define PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE	(1 << 5) /* Output of PWM right after startup enabled to help ESCs initialize and prevent them from beeping */
-#define PX4IO_P_SETUP_ARMING_RC_HANDLING_DISABLED	(1 << 6) /* Disable the IO-internal evaluation of the RC */
-#define PX4IO_P_SETUP_ARMING_LOCKDOWN		(1 << 7) /* If set, the system operates normally, but won't actuate any servos */
-#define PX4IO_P_SETUP_ARMING_FORCE_FAILSAFE	(1 << 8) /* If set, the system will always output the failsafe values */
-#define PX4IO_P_SETUP_ARMING_TERMINATION_FAILSAFE	(1 << 9) /* If set, the system will never return from a failsafe, but remain in failsafe once triggered. */
-#define PX4IO_P_SETUP_ARMING_OVERRIDE_IMMEDIATE	(1 << 10) /* If set then on FMU failure override is immediate. Othewise it waits for the mode switch to go past the override thrshold */
+#define PX4IO_P_SETUP_ARMING_FMU_PREARMED	(1 << 2) /* FMU is already prearmed */
+#define PX4IO_P_SETUP_ARMING_MANUAL_OVERRIDE_OK	(1 << 3) /* OK to switch to manual override via override RC channel */
+#define PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM	(1 << 4) /* use custom failsafe values, not 0 values of mixer */
+#define PX4IO_P_SETUP_ARMING_INAIR_RESTART_OK	(1 << 5) /* OK to try in-air restart */
+#define PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE	(1 << 6) /* Output of PWM right after startup enabled to help ESCs initialize and prevent them from beeping */
+#define PX4IO_P_SETUP_ARMING_RC_HANDLING_DISABLED	(1 << 7) /* Disable the IO-internal evaluation of the RC */
+#define PX4IO_P_SETUP_ARMING_LOCKDOWN		(1 << 8) /* If set, the system operates normally, but won't actuate any servos */
+#define PX4IO_P_SETUP_ARMING_FORCE_FAILSAFE	(1 << 9) /* If set, the system will always output the failsafe values */
+#define PX4IO_P_SETUP_ARMING_TERMINATION_FAILSAFE	(1 << 10) /* If set, the system will never return from a failsafe, but remain in failsafe once triggered. */
+#define PX4IO_P_SETUP_ARMING_OVERRIDE_IMMEDIATE	(1 << 11) /* If set then on FMU failure override is immediate. Othewise it waits for the mode switch to go past the override thrshold */
 
 #define PX4IO_P_SETUP_PWM_RATES			2	/* bitmask, 0 = low rate, 1 = high rate */
 #define PX4IO_P_SETUP_PWM_DEFAULTRATE		3	/* 'low' PWM frame output rate in Hz */
diff --git a/src/modules/px4iofirmware/registers.c b/src/modules/px4iofirmware/registers.c
index 8cd9d909e1..1e43a5fb80 100644
--- a/src/modules/px4iofirmware/registers.c
+++ b/src/modules/px4iofirmware/registers.c
@@ -191,6 +191,7 @@ volatile uint16_t	r_page_setup[] = {
 		PX4IO_P_SETUP_FEATURES_PWM_RSSI)
 
 #define PX4IO_P_SETUP_ARMING_VALID	(PX4IO_P_SETUP_ARMING_FMU_ARMED | \
+		PX4IO_P_SETUP_ARMING_FMU_PREARMED | \
 		PX4IO_P_SETUP_ARMING_MANUAL_OVERRIDE_OK | \
 		PX4IO_P_SETUP_ARMING_INAIR_RESTART_OK | \
 		PX4IO_P_SETUP_ARMING_IO_ARM_OK | \