diff --git a/header.go b/header.go
index a037314..f710904 100644
--- a/header.go
+++ b/header.go
@@ -44,7 +44,7 @@ func GetDomain(req *http.Request) string {
 	var host string = GetHost(req)
 	hosts := strings.Split(host, ":")
 	host = hosts[0]
-	if hosts[1] == "443" {
+	if len(hosts) > 1 && hosts[1] == "443" {
 		scheme = "https://"
 	}
 	var w strings.Builder