diff --git a/Tools/autotest/common.py b/Tools/autotest/common.py
index 7088b003db..5ffea5c85b 100644
--- a/Tools/autotest/common.py
+++ b/Tools/autotest/common.py
@@ -5491,7 +5491,7 @@ switch value'''
         m = self.mav.recv_match(type='GLOBAL_POSITION_INT', blocking=True, timeout=1)
         if m is None:
             raise NotAchievedException("Did not receive GLOBAL_POSITION_INT")
-        gpi_abs_alt = int(m.alt / 1000) # mm -> m
+        gpi_abs_alt = int((m.alt+500) / 1000) # mm -> m
         tstart = self.get_sim_time_cached()
         while True:
             t2 = self.get_sim_time_cached()