diff --git a/powerwall.sh b/powerwall.sh
index 6dd5f9be..60938b77 100755
--- a/powerwall.sh
+++ b/powerwall.sh
@@ -25,9 +25,9 @@ CHECKTEMP(){
 		echo ${TEMP_THRESHOLDS[${1}]} | cut -d',' -f 1 | read temp_warn
 		echo ${TEMP_THRESHOLDS[${1}]} | cut -d',' -f 2 | read temp_crit
 		
-		if [ $temp_f -ge ${temp_warn} ] && [ $temp_f -lt ${temp_crit} ]; then
+		if [ $temp_f -ge $(($temp_warn)) ] && [ $temp_f -lt $(($temp_crit)) ]; then
 			echo "WARNING: $temp_f"
-		elif [ $temp_f -ge ${temp_crit} ]; then
+		elif [ $temp_f -ge $(($temp_crit)) ]; then
 			echo "CRITICAL: $temp_f"
 		else
 			echo "normal: $temp_f"