diff --git a/timeout b/timeout
index cb2de2a..022dcda 100755
--- a/timeout
+++ b/timeout
@@ -31,7 +31,7 @@ check_pid() {
 	PID=$1
 	LOOP=$2
 
-	for _ in $(seq 1 "$(($LOOP*2))"); do
+	for _ in $(seq 1 "$((LOOP*2))"); do
 		test -d "/proc/$PID/" && sleep 0.5 || STATUS=0
 	done