diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 74d25786f..c4b6a79e0 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -58,12 +58,12 @@ def add_mention_tags(object) do
     mentions = object["to"]
     |> Enum.map(fn (ap_id) -> User.get_cached_by_ap_id(ap_id) end)
     |> Enum.filter(&(&1))
-    |> Enum.map(fn(user) -> %{"type" => "mention", "href" => user.ap_id, "name" => "@#{user.nickname}"} end)
+    |> Enum.map(fn(user) -> %{"type" => "Mention", "href" => user.ap_id, "name" => "@#{user.nickname}"} end)
 
-    tags = object["tags"] || []
+    tags = object["tag"] || []
 
     object
-    |> Map.put("tags", tags ++ mentions)
+    |> Map.put("tag", tags ++ mentions)
   end
 
   def add_attributed_to(object) do
diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 76dc6d4ad..124a5703b 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -45,10 +45,10 @@ test "it turns mentions into tags" do
       expected_tag = %{
         "href" => other_user.ap_id,
         "name" => "@#{other_user.nickname}",
-        "type" => "mention"
+        "type" => "Mention"
       }
 
-      assert Enum.member?(object["tags"], expected_tag)
+      assert Enum.member?(object["tag"], expected_tag)
     end
 
     test "it adds the json-ld context" do