diff --git a/Tools/autotest/pysim/sim_multicopter.py b/Tools/autotest/pysim/sim_multicopter.py
index 42058a67ee..ef25d4cd13 100755
--- a/Tools/autotest/pysim/sim_multicopter.py
+++ b/Tools/autotest/pysim/sim_multicopter.py
@@ -197,4 +197,6 @@ while True:
         time.sleep(last_wall_time+scaled_frame_time - now)
     last_wall_time = time.time()
 
-    a.time_advance(frame_time)
+    if frame_start == a.time_now:
+        # time has not been advanced by a.update()
+        a.time_advance(frame_time)