diff --git a/docs/en/Tutorials/Part-8.md b/docs/en/Tutorials/Part-8.md
index 24dafffdb9..9d638e909e 100644
--- a/docs/en/Tutorials/Part-8.md
+++ b/docs/en/Tutorials/Part-8.md
@@ -102,7 +102,7 @@ namespace Acme.BookStore.Authors;
 
 public class GetAuthorListDto : PagedAndSortedResultRequestDto
 {
-    public string Filter { get; set; }
+    public string? Filter { get; set; }
 }
 ````
 
diff --git a/docs/zh-Hans/Tutorials/Part-8.md b/docs/zh-Hans/Tutorials/Part-8.md
index d3b78de7e0..5c58d1b524 100644
--- a/docs/zh-Hans/Tutorials/Part-8.md
+++ b/docs/zh-Hans/Tutorials/Part-8.md
@@ -107,7 +107,7 @@ namespace Acme.BookStore.Authors
 {
     public class GetAuthorListDto : PagedAndSortedResultRequestDto
     {
-        public string Filter { get; set; }
+        public string? Filter { get; set; }
     }
 }
 ````