diff --git a/lib/pleroma/web/activity_pub/activity_pub_controller.ex b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
index 01b34fb1d..34bf04a20 100644
--- a/lib/pleroma/web/activity_pub/activity_pub_controller.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
@@ -293,6 +293,7 @@ def internal_fetch(conn, _params) do
     |> represent_service_actor(conn)
   end
 
+  @doc "Returns the authenticated user's ActivityPub User object or a 404 Not Found if non-authenticated"
   def whoami(%{assigns: %{user: %User{} = user}} = conn, _params) do
     conn
     |> put_resp_content_type("application/activity+json")
diff --git a/test/web/activity_pub/activity_pub_controller_test.exs b/test/web/activity_pub/activity_pub_controller_test.exs
index 9e8e420ec..0f8638a94 100644
--- a/test/web/activity_pub/activity_pub_controller_test.exs
+++ b/test/web/activity_pub/activity_pub_controller_test.exs
@@ -976,4 +976,19 @@ test "it tracks a signed activity fetch when the json is cached", %{conn: conn}
       assert Delivery.get(object.id, other_user.id)
     end
   end
+
+  describe "Additionnal ActivityPub C2S endpoints" do
+    test "/api/ap/whoami", %{conn: conn} do
+      user = insert(:user)
+
+      conn =
+        conn
+        |> assign(:user, user)
+        |> get("/api/ap/whoami")
+
+      user = User.get_cached_by_id(user.id)
+
+      assert UserView.render("user.json", %{user: user}) == json_response(conn, 200)
+    end
+  end
 end