diff --git a/wchat/wx/SecCheck.php b/wchat/wx/SecCheck.php
index 50f1d57..d2d135a 100644
--- a/wchat/wx/SecCheck.php
+++ b/wchat/wx/SecCheck.php
@@ -13,11 +13,11 @@ use wchat\common\Result;
 class SecCheck extends SmallProgram
 {
 
-    private string $_url = '/wxa/img_sec_check?access_token=';
+    private $_url = '/wxa/img_sec_check?access_token=';
 
-    private string $_msgUrl = '/wxa/msg_sec_check?access_token=';
+    private $_msgUrl = '/wxa/msg_sec_check?access_token=';
 
-    private string $_mediaCheckAsync = '/wxa/media_check_async?access_token=';
+    private $_mediaCheckAsync = '/wxa/media_check_async?access_token=';
 
 	const MEDIA_VIDEO = 1;
 	const MEDIA_IMAGE = 1;