diff --git a/app/crm/utils/Util.php b/app/crm/utils/Util.php
index 7bf4efd..7385e76 100644
--- a/app/crm/utils/Util.php
+++ b/app/crm/utils/Util.php
@@ -134,7 +134,7 @@ class Util
         if($length <= 6){
             return $str;
         }
-        return substr($str, 0, 3) . '****' . substr($str, -4);
+        return mb_substr($str, 0, 3) . '****' . mb_substr($str, -4);
     }
 
 }
\ No newline at end of file