diff --git a/Tools/autotest/ardusub.py b/Tools/autotest/ardusub.py
index a6af0aba9c..e78bed5de7 100644
--- a/Tools/autotest/ardusub.py
+++ b/Tools/autotest/ardusub.py
@@ -373,12 +373,12 @@ class AutoTestSub(AutoTest):
 
     def reboot_sitl(self):
         """Reboot SITL instance and wait it to reconnect."""
-        # out battery is reset to full on reboot.  So reduce it to 10%
+        # our battery is reset to full on reboot.  So reduce it to 10%
         # and wait for it to go above 50.
         self.run_cmd(
             mavutil.mavlink.MAV_CMD_BATTERY_RESET,
-            p1=255,  # battery mask
-            p2=10,   # percentage
+            p1=65535,   # battery mask
+            p2=10,      # percentage
         )
         self.run_cmd_reboot()
         tstart = time.time()
diff --git a/Tools/autotest/common.py b/Tools/autotest/common.py
index f0c6cde6ab..23acfa6056 100644
--- a/Tools/autotest/common.py
+++ b/Tools/autotest/common.py
@@ -12691,8 +12691,8 @@ switch value'''
         # grab a battery-remaining percentage
         self.run_cmd(
             mavutil.mavlink.MAV_CMD_BATTERY_RESET,
-            p1=255,  # battery mask
-            p2=96,   # percentage
+            p1=65535,   # battery mask
+            p2=96,      # percentage
         )
         m = self.assert_receive_message('BATTERY_STATUS', timeout=1)
         want_battery_remaining_pct = m.battery_remaining