diff --git a/CreativeWorks/Book.cs b/CreativeWorks/Book.cs
index a3a744a..2f448d9 100644
--- a/CreativeWorks/Book.cs
+++ b/CreativeWorks/Book.cs
@@ -57,7 +57,7 @@ public class Book : CreativeWork, MXTires.Microdata.CreativeWorks.IBook
         /// Text - The ISBN of the book.
         /// </summary>
         [JsonProperty("isbn")]
-        public Person Isbn { get; set; }
+        public string Isbn { get; set; }
 
         /// <summary>
         /// Integer - The number of pages in the book.
@@ -65,4 +65,4 @@ public class Book : CreativeWork, MXTires.Microdata.CreativeWorks.IBook
         [JsonProperty("numberOfPages")]
         public Int32? NumberOfPages { get; set; }
     }
-}
\ No newline at end of file
+}