diff --git a/powerwall.sh b/powerwall.sh
index 2c4e6847..bd4bb602 100755
--- a/powerwall.sh
+++ b/powerwall.sh
@@ -613,9 +613,9 @@ TEST(){
 	temptotal=0
 	while IFS=$'\t' read date sensorid temp hum ;do
 		# echo date:$date sensorid:$sensorid temp:$temp hum:$hum
-		temptotal=`expr ${temptotal} + ${temp}`
+		temptotal=$(expr ${temptotal} + ${temp})
 		echo "- ${temptotal} + ${temp}"
-	done  < <(${mysql_conn} -se "USE servermonitor; SELECT date,sensorid,temp,hum from sensor_data WHERE sensorid=2 ORDER BY id DESC LIMIT 10000;")
+	done  < <(${mysql_conn} -se "USE servermonitor; SELECT date,sensorid,temp,hum from sensor_data WHERE sensorid=2 ORDER BY id DESC LIMIT 10;")
 	
 	average=$(bc <<< "scale=2; ${temptotal}/10000")