diff --git a/hook/hook.go b/hook/hook.go
index f5e20ad..79f624a 100644
--- a/hook/hook.go
+++ b/hook/hook.go
@@ -196,7 +196,7 @@ func CheckIPWhitelist(remoteAddr string, ipRange string) (bool, error) {
 
 	ipRange = strings.TrimSpace(ipRange)
 
-	if strings.Index(ipRange, "/") == -1 {
+	if !strings.Contains(ipRange, "/") {
 		ipRange = ipRange + "/32"
 	}