diff --git a/library/think/Input.php b/library/think/Input.php
index 8eec91ce..bfed8a20 100644
--- a/library/think/Input.php
+++ b/library/think/Input.php
@@ -288,14 +288,11 @@ class Input
      */
     private static function regexFilter($input, $filter)
     {
-        if(empty($filter_)){
+        if (empty($filter) || is_array($input)) {
             return null;
         }
         $begin = $filter[0];
         $end   = $filter[strlen($filter) - 1];
-        if (is_array($input)) {
-            return null;
-        }
         if (
             ('/' === $begin && '/' === $end) ||
             ('#' === $begin && '#' === $end) ||