diff --git a/prog/pwm/fancontrol b/prog/pwm/fancontrol
index 448b3d47..b6391f40 100755
--- a/prog/pwm/fancontrol
+++ b/prog/pwm/fancontrol
@@ -45,6 +45,8 @@ MAX=255
 
 echo $$ > /var/run/fancontrol.pid
 
+declare -i pwmval
+
 function LoadConfig {
 	echo "Loading configuration from $1 ..."
 	# grep configuration from file
@@ -324,7 +326,7 @@ function UpdateFanSpeeds {
 		  then pwmval=$maxpwm # over max temp, use defined max pwm
 		else 
 		  # calculate the new value from temperature and settings
-		  let pwmval="(${tval}-${mint})*(${maxpwm}-${minso})/(${maxt}-${mint})+${minso}"
+		  pwmval="(${tval}-${mint})*(${maxpwm}-${minso})/(${maxt}-${mint})+${minso}"
 		  if [ $pwmpval -eq 0 -o $fanval -eq 0 ]
 		  then # if fan was stopped start it using a safe value
 		  	echo $minsa > $pwmo