diff --git a/src/modules/mavlink/mavlink_main.h b/src/modules/mavlink/mavlink_main.h
index ccff6614f8..cc4c896b91 100644
--- a/src/modules/mavlink/mavlink_main.h
+++ b/src/modules/mavlink/mavlink_main.h
@@ -209,7 +209,7 @@ private:
 
 	orb_advert_t	_mission_pub;
 	struct mission_s mission;
-	uint8_t missionlib_msg_buf[sizeof(mavlink_message_t)];
+	uint8_t missionlib_msg_buf[MAVLINK_MAX_PACKET_LEN];
 	MAVLINK_MODE _mode;
 
 	uint8_t _mavlink_wpm_comp_id;