diff --git a/lib/Models/CoreTypes/object.dart b/lib/Models/CoreTypes/object.dart
new file mode 100644
index 0000000..3d3db3a
--- /dev/null
+++ b/lib/Models/CoreTypes/object.dart
@@ -0,0 +1,3 @@
+class ActivityPubObject {
+  List<ActivityPubObject>? attachments;
+}
diff --git a/lib/Models/ObjectTypes/document.dart b/lib/Models/ObjectTypes/document.dart
index 7312f03..1ea2cdb 100644
--- a/lib/Models/ObjectTypes/document.dart
+++ b/lib/Models/ObjectTypes/document.dart
@@ -1,4 +1,6 @@
-class Document {
+import 'package:activitypub/Models/CoreTypes/object.dart';
+
+class Document extends ActivityPubObject {
   final String type;
   final String? name;
   final String? mediaType;
diff --git a/lib/Models/post.dart b/lib/Models/post.dart
index b80e8c5..80c533d 100644
--- a/lib/Models/post.dart
+++ b/lib/Models/post.dart
@@ -1,9 +1,9 @@
 import 'dart:core';
 import 'package:activitypub/Models/ObjectTypes/document.dart';
-
+import 'CoreTypes/object.dart';
 import 'collection.dart';
 
-class Post {
+class Post extends ActivityPubObject {
   final List<String> to;
   final String? name;
   final String? summary;
diff --git a/pubspec.yaml b/pubspec.yaml
index 9788ee3..737fa57 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: activitypub
 description: A library for the ActivityPub standard. Created an also used by Fedodo.
-version: 1.2.3
+version: 1.2.4
 repository: https://github.com/Fedodo/Fedodo.Pub.ActivityPub
 
 environment: