1 files changed, 7 insertions, 0 deletions
diff --git a/app/serializers/activitypub/note_serializer.rb b/app/serializers/activitypub/note_serializer.rb
index 4061b9ce4..15031dfdc 100644
--- a/app/serializers/activitypub/note_serializer.rb
+++ b/app/serializers/activitypub/note_serializer.rb
@@ -9,6 +9,7 @@ class ActivityPub::NoteSerializer < ActiveModel::Serializer
   has_many :virtual_tags, key: :tag
 
   attribute :atom_uri, key: '_:atomUri', if: :local?
+  attribute :in_reply_to_atom_uri, key: '_:inReplyToAtomUri'
 
   def id
     ActivityPub::TagManager.instance.uri_for(object)
@@ -64,6 +65,12 @@ class ActivityPub::NoteSerializer < ActiveModel::Serializer
     ::TagManager.instance.uri_for(object)
   end
 
+  def in_reply_to_atom_uri
+    return unless object.reply?
+
+    ::TagManager.instance.uri_for(object.thread)
+  end
+
   def local?
     object.account.local?
   end