diff --git a/lib/pleroma/web/ostatus/activity_representer.ex b/lib/pleroma/web/ostatus/activity_representer.ex
index 30e695bcc..07b9033b9 100644
--- a/lib/pleroma/web/ostatus/activity_representer.ex
+++ b/lib/pleroma/web/ostatus/activity_representer.ex
@@ -1,4 +1,19 @@
 defmodule Pleroma.Web.OStatus.ActivityRepresenter do
+  alias Pleroma.Activity
+  require Logger
+
+  defp get_in_reply_to(%{"object" => %{ "inReplyTo" => in_reply_to}}) do
+    with %Activity{data: %{"id" => id}} <- Activity.get_create_activity_by_object_ap_id(in_reply_to) do
+      [{:"thr:in-reply-to", [ref: to_charlist(id)], []}]
+    else _e ->
+      Logger.debug("Couldn't find replied-to activity:")
+      Logger.debug(in_reply_to)
+      []
+    end
+  end
+
+  defp get_in_reply_to(_), do: []
+
   def to_simple_form(%{data: %{"object" => %{"type" => "Note"}}} = activity, user) do
     h = fn(str) -> [to_charlist(str)] end
 
@@ -12,6 +27,8 @@ def to_simple_form(%{data: %{"object" => %{"type" => "Note"}}} = activity, user)
       {:link, [rel: 'enclosure', href: to_charlist(url["href"]), type: to_charlist(url["mediaType"])], []}
     end)
 
+    in_reply_to = get_in_reply_to(activity.data)
+
     [
       {:"activity:object-type", ['http://activitystrea.ms/schema/1.0/note']},
       {:"activity:verb", ['http://activitystrea.ms/schema/1.0/post']},
@@ -22,7 +39,7 @@ def to_simple_form(%{data: %{"object" => %{"type" => "Note"}}} = activity, user)
       {:updated, h.(updated_at)},
       {:"ostatus:conversation", [], h.(activity.data["context"])},
       {:link, [href: h.(activity.data["context"]), rel: 'ostatus:conversation'], []}
-    ] ++ attachments
+    ] ++ attachments ++ in_reply_to
   end
 
   def to_simple_form(_,_), do: nil
diff --git a/lib/pleroma/web/ostatus/feed_representer.ex b/lib/pleroma/web/ostatus/feed_representer.ex
index 10a1ffb25..db7b685f3 100644
--- a/lib/pleroma/web/ostatus/feed_representer.ex
+++ b/lib/pleroma/web/ostatus/feed_representer.ex
@@ -16,6 +16,7 @@ def to_simple_form(user, activities, users) do
     [{
       :feed, [
         xmlns: 'http://www.w3.org/2005/Atom',
+        "xmlns:thr": 'http://purl.org/syndication/thread/1.0',
         "xmlns:activity": 'http://activitystrea.ms/spec/1.0/',
         "xmlns:poco": 'http://portablecontacts.net/spec/1.0',
         "xmlns:ostatus": 'http://ostatus.org/schema/1.0'
diff --git a/test/web/ostatus/activity_representer_test.exs b/test/web/ostatus/activity_representer_test.exs
index 6cea9cff0..fd1b1598c 100644
--- a/test/web/ostatus/activity_representer_test.exs
+++ b/test/web/ostatus/activity_representer_test.exs
@@ -34,6 +34,42 @@ test "a note activity" do
     assert clean(res) == clean(expected)
   end
 
+  test "a reply note" do
+    note = insert(:note_activity)
+    answer = insert(:note_activity)
+    object = answer.data["object"]
+    object = Map.put(object, "inReplyTo", note.data["object"]["id"])
+
+    data = %{answer.data | "object" => object}
+    answer = %{answer | data: data}
+
+    updated_at = answer.updated_at
+    |> NaiveDateTime.to_iso8601
+    inserted_at = answer.inserted_at
+    |> NaiveDateTime.to_iso8601
+
+    user = User.get_cached_by_ap_id(answer.data["actor"])
+
+    expected = """
+    <activity:object-type>http://activitystrea.ms/schema/1.0/note</activity:object-type>
+    <activity:verb>http://activitystrea.ms/schema/1.0/post</activity:verb>
+    <id>#{answer.data["id"]}</id>
+    <title>New note by #{user.nickname}</title>
+    <content type="html">#{answer.data["object"]["content"]}</content>
+    <published>#{inserted_at}</published>
+    <updated>#{updated_at}</updated>
+    <ostatus:conversation>#{answer.data["context"]}</ostatus:conversation>
+    <link href="#{answer.data["context"]}" rel="ostatus:conversation" />
+    <thr:in-reply-to ref="#{note.data["id"]}" />
+    """
+
+    tuple = ActivityRepresenter.to_simple_form(answer, user)
+
+    res = :xmerl.export_simple_content(tuple, :xmerl_xml) |> IO.iodata_to_binary
+
+    assert clean(res) == clean(expected)
+  end
+
   test "an unknown activity" do
     tuple = ActivityRepresenter.to_simple_form(%Activity{}, nil)
     assert is_nil(tuple)