diff --git a/library/think/Request.php b/library/think/Request.php
index 803a5240..c4dad8b7 100644
--- a/library/think/Request.php
+++ b/library/think/Request.php
@@ -1034,11 +1034,7 @@ class Request
             $filter = [];
         } else {
             $filter = $filter ?: $this->filter;
-            if (is_string($filter)) {
-                $filter = explode(',', $filter);
-            } else {
-                $filter = (array) $filter;
-            }
+            $filter = (array) $filter;
         }
 
         $filter[] = $default;