diff --git a/mavutil.py b/mavutil.py
index 3637b03e7..a94a58bf3 100644
--- a/mavutil.py
+++ b/mavutil.py
@@ -423,9 +423,9 @@ def post_message(self, msg):
                 self.flightmode = mode_string_v10(msg)
                 self.mav_type = msg.type
                 self.base_mode = msg.base_mode
-                self.sysid_state[self.sysid].armed = (msg.base_mode & mavlink.MAV_MODE_FLAG_SAFETY_ARMED)
-                self.sysid_state[self.sysid].mav_type = msg.type
-                self.sysid_state[self.sysid].mav_autopilot = msg.autopilot
+                self.sysid_state[src_system].armed = (msg.base_mode & mavlink.MAV_MODE_FLAG_SAFETY_ARMED)
+                self.sysid_state[src_system].mav_type = msg.type
+                self.sysid_state[src_system].mav_autopilot = msg.autopilot
         elif type == 'HIGH_LATENCY2':
             if self.sysid == 0:
                 # lock onto id tuple of first vehicle heartbeat
@@ -434,9 +434,9 @@ def post_message(self, msg):
             self.mav_type = msg.type
             if msg.autopilot == mavlink.MAV_AUTOPILOT_ARDUPILOTMEGA:
                 self.base_mode = msg.custom0
-                self.sysid_state[self.sysid].armed = (msg.custom0 & mavlink.MAV_MODE_FLAG_SAFETY_ARMED)
-            self.sysid_state[self.sysid].mav_type = msg.type
-            self.sysid_state[self.sysid].mav_autopilot = msg.autopilot
+                self.sysid_state[src_system].armed = (msg.custom0 & mavlink.MAV_MODE_FLAG_SAFETY_ARMED)
+            self.sysid_state[src_system].mav_type = msg.type
+            self.sysid_state[src_system].mav_autopilot = msg.autopilot
 
         elif type == 'PARAM_VALUE':
             if not src_tuple in self.param_state: