diff --git a/Tools/autotest/arducopter.py b/Tools/autotest/arducopter.py
index 994886c1e0..6d5f4c01c4 100644
--- a/Tools/autotest/arducopter.py
+++ b/Tools/autotest/arducopter.py
@@ -2,7 +2,7 @@
 
 import util, pexpect, sys, time, math, shutil, os
 from common import *
-import mavutil, mavwp
+import mavutil, mavwp, random
 
 # get location of scripts
 testdir=os.path.dirname(os.path.realpath(__file__))
@@ -247,6 +247,7 @@ def fly_ArduCopter(viewerip=None):
     mavproxy.expect('Received [0-9]+ parameters')
 
     # setup test parameters
+    mavproxy.send('param set SYSID_THISMAV %u\n' % random.randint(100, 200))
     mavproxy.send("param load %s/ArduCopter.parm\n" % testdir)
     mavproxy.expect('Loaded [0-9]+ parameters')
 
diff --git a/Tools/autotest/arduplane.py b/Tools/autotest/arduplane.py
index badd267940..80fecede4f 100644
--- a/Tools/autotest/arduplane.py
+++ b/Tools/autotest/arduplane.py
@@ -2,7 +2,7 @@
 
 import util, pexpect, sys, time, math, shutil, os
 from common import *
-import mavutil
+import mavutil, random
 
 # get location of scripts
 testdir=os.path.dirname(os.path.realpath(__file__))
@@ -206,6 +206,7 @@ def fly_ArduPlane(viewerip=None):
     mavproxy.expect('Received [0-9]+ parameters')
 
     # setup test parameters
+    mavproxy.send('param set SYSID_THISMAV %u\n' % random.randint(100, 200))
     mavproxy.send("param load %s/ArduPlane.parm\n" % testdir)
     mavproxy.expect('Loaded [0-9]+ parameters')