diff --git a/types/utils.go b/types/utils.go
index 6285674..51e3983 100644
--- a/types/utils.go
+++ b/types/utils.go
@@ -82,7 +82,7 @@ func CopyBytes(bz []byte) (ret []byte) {
 // GetTLSCertPool get certificates from target server
 func GetTLSCertPool(gateWayURL string) ([]*x509.Certificate, error) {
 	if !strings.Contains(strings.ToLower(gateWayURL), "https://") {
-		return nil, errors.New("TLS is enabled, but the address is http")
+		return nil, errors.New("this function requires HTTPS protocol")
 	}
 	tr := &http.Transport{
 		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},