diff --git a/samples/BookStore/src/Acme.BookStore.Application/CreateUpdateBookDto.cs b/samples/BookStore/src/Acme.BookStore.Application/CreateUpdateBookDto.cs
index f64a1d36e0..0d5dae71cb 100644
--- a/samples/BookStore/src/Acme.BookStore.Application/CreateUpdateBookDto.cs
+++ b/samples/BookStore/src/Acme.BookStore.Application/CreateUpdateBookDto.cs
@@ -11,7 +11,8 @@ namespace Acme.BookStore
         [Required]
         [StringLength(128)]
         public string Name { get; set; }
-        
+
+        [Required]
         public BookType Type { get; set; } = BookType.Undefined;
         
         [Required]