diff --git a/src/modules/mavlink/mavlink.c b/src/modules/mavlink/mavlink.c
index bec706badd..9afe74af1c 100644
--- a/src/modules/mavlink/mavlink.c
+++ b/src/modules/mavlink/mavlink.c
@@ -78,11 +78,7 @@ PARAM_DEFINE_INT32(MAV_FWDEXTSP, 1);
 
 mavlink_system_t mavlink_system = {
 	100,
-	50,
-	MAV_TYPE_FIXED_WING,
-	0,
-	0,
-	0
+	50
 }; // System ID, 1-255, Component/Subsystem ID, 1-255
 
 /*
diff --git a/src/modules/mavlink/mavlink_main.cpp b/src/modules/mavlink/mavlink_main.cpp
index 6b4edff78a..c251dd3b2c 100644
--- a/src/modules/mavlink/mavlink_main.cpp
+++ b/src/modules/mavlink/mavlink_main.cpp
@@ -167,8 +167,10 @@ Mavlink::Mavlink() :
 	_param_initialized(false),
 	_param_system_id(0),
 	_param_component_id(0),
-	_param_system_type(0),
+	_param_system_type(MAV_TYPE_FIXED_WING),
 	_param_use_hil_gps(0),
+	_param_forward_externalsp(0),
+	_system_type(0),
 
 	/* performance counters */
 	_loop_perf(perf_alloc(PC_ELAPSED, "mavlink_el")),
@@ -524,7 +526,7 @@ void Mavlink::mavlink_update_system(void)
 	param_get(_param_system_type, &system_type);
 
 	if (system_type >= 0 && system_type < MAV_TYPE_ENUM_END) {
-		mavlink_system.type = system_type;
+		_system_type = system_type;
 	}
 
 	int32_t use_hil_gps;
@@ -755,7 +757,7 @@ Mavlink::send_message(const uint8_t msgid, const void *msg)
 
 	pthread_mutex_lock(&_send_mutex);
 
-	int buf_free = get_free_tx_buf();
+	unsigned buf_free = get_free_tx_buf();
 
 	uint8_t payload_len = mavlink_message_lengths[msgid];
 	unsigned packet_len = payload_len + MAVLINK_NUM_NON_PAYLOAD_BYTES;
@@ -820,14 +822,14 @@ Mavlink::resend_message(mavlink_message_t *msg)
 
 	pthread_mutex_lock(&_send_mutex);
 
-	int buf_free = get_free_tx_buf();
+	unsigned buf_free = get_free_tx_buf();
 
 	_last_write_try_time = hrt_absolute_time();
 
 	unsigned packet_len = msg->len + MAVLINK_NUM_NON_PAYLOAD_BYTES;
 
 	/* check if there is space in the buffer, let it overflow else */
-	if (buf_free < TX_BUFFER_GAP) {
+	if ((buf_free < TX_BUFFER_GAP) || (buf_free < packet_len)) {
 		/* no enough space in buffer to send */
 		count_txerr();
 		count_txerrbytes(packet_len);
diff --git a/src/modules/mavlink/mavlink_main.h b/src/modules/mavlink/mavlink_main.h
index 1f96e586bb..ad5e5001b9 100644
--- a/src/modules/mavlink/mavlink_main.h
+++ b/src/modules/mavlink/mavlink_main.h
@@ -265,6 +265,8 @@ public:
 
 	struct mavlink_logbuffer	*get_logbuffer() { return &_logbuffer; }
 
+	unsigned		get_system_type() { return _system_type; }
+
 protected:
 	Mavlink			*next;
 
@@ -354,6 +356,8 @@ private:
 	param_t			_param_use_hil_gps;
 	param_t			_param_forward_externalsp;
 
+	unsigned		_system_type;
+
 	perf_counter_t		_loop_perf;			/**< loop performance counter */
 	perf_counter_t		_txerr_perf;			/**< TX error counter */
 
diff --git a/src/modules/mavlink/mavlink_messages.cpp b/src/modules/mavlink/mavlink_messages.cpp
index cccb698bf9..b4911427f6 100644
--- a/src/modules/mavlink/mavlink_messages.cpp
+++ b/src/modules/mavlink/mavlink_messages.cpp
@@ -302,7 +302,7 @@ protected:
 		msg.base_mode = 0;
 		msg.custom_mode = 0;
 		get_mavlink_mode_state(&status, &pos_sp_triplet, &msg.system_status, &msg.base_mode, &msg.custom_mode);
-		msg.type = mavlink_system.type;
+		msg.type = _mavlink->get_system_type();
 		msg.autopilot = MAV_AUTOPILOT_PX4;
 		msg.mavlink_version = 3;
 
@@ -1353,15 +1353,17 @@ protected:
 
 			const float pwm_center = (PWM_HIGHEST_MAX + PWM_LOWEST_MIN) / 2;
 
+			unsigned system_type = _mavlink->get_system_type();
+
 			/* scale outputs depending on system type */
-			if (mavlink_system.type == MAV_TYPE_QUADROTOR ||
-				mavlink_system.type == MAV_TYPE_HEXAROTOR ||
-				mavlink_system.type == MAV_TYPE_OCTOROTOR) {
+			if (system_type == MAV_TYPE_QUADROTOR ||
+				system_type == MAV_TYPE_HEXAROTOR ||
+				system_type == MAV_TYPE_OCTOROTOR) {
 				/* multirotors: set number of rotor outputs depending on type */
 
 				unsigned n;
 
-				switch (mavlink_system.type) {
+				switch (system_type) {
 				case MAV_TYPE_QUADROTOR:
 					n = 4;
 					break;