diff --git a/dsmon.sh b/dsmon.sh
index 2bcbf6c..131591a 100755
--- a/dsmon.sh
+++ b/dsmon.sh
@@ -168,7 +168,7 @@ CHECK(){
 			for DRIVE in "${DRIVES[@]}"; do
 
 				WARNING_LEVEL=$(expr 100 - ${host_limits_tmp[$DRIVE]})
-				CRITICAL_LEVEL=$(printf "%0.2f" $(jq -n $WARNING_LEVEL-($WARNING_LEVEL/2)))
+				CRITICAL_LEVEL=$(printf "%0.2f" $(jq -n $WARNING_LEVEL-$WARNING_LEVEL/2))
 				
 				echo "warn=$WARNING_LEVEL - crit=$CRITICAL_LEVEL"