diff --git a/lib/pleroma/plugs/set_format_plug.ex b/lib/pleroma/plugs/set_format_plug.ex
new file mode 100644
index 000000000..5ca741c64
--- /dev/null
+++ b/lib/pleroma/plugs/set_format_plug.ex
@@ -0,0 +1,24 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Plugs.SetFormatPlug do
+  import Plug.Conn, only: [assign: 3, fetch_query_params: 1]
+
+  def init(_), do: nil
+
+  def call(conn, _) do
+    case get_format(conn) do
+      nil -> conn
+      format -> assign(conn, :format, format)
+    end
+  end
+
+  defp get_format(conn) do
+    conn.private[:phoenix_format] ||
+      case fetch_query_params(conn) do
+        %{query_params: %{"_format" => format}} -> format
+        _ -> nil
+      end
+  end
+end
diff --git a/lib/pleroma/web/web_finger/web_finger.ex b/lib/pleroma/web/web_finger/web_finger.ex
index fa34c7ced..0514ade2b 100644
--- a/lib/pleroma/web/web_finger/web_finger.ex
+++ b/lib/pleroma/web/web_finger/web_finger.ex
@@ -187,6 +187,7 @@ def find_lrdd_template(domain) do
     end
   end
 
+  @spec finger(String.t()) :: {:ok, map()} | {:error, any()}
   def finger(account) do
     account = String.trim_leading(account, "@")
 
@@ -220,8 +221,6 @@ def finger(account) do
       else
         with {:ok, doc} <- Jason.decode(body) do
           webfinger_from_json(doc)
-        else
-          {:error, e} -> e
         end
       end
     else
diff --git a/lib/pleroma/web/web_finger/web_finger_controller.ex b/lib/pleroma/web/web_finger/web_finger_controller.ex
index b77c75ec5..896eb15f9 100644
--- a/lib/pleroma/web/web_finger/web_finger_controller.ex
+++ b/lib/pleroma/web/web_finger/web_finger_controller.ex
@@ -7,6 +7,7 @@ defmodule Pleroma.Web.WebFinger.WebFingerController do
 
   alias Pleroma.Web.WebFinger
 
+  plug(Pleroma.Plugs.SetFormatPlug)
   plug(Pleroma.Web.FederatingPlug)
 
   def host_meta(conn, _params) do
@@ -17,30 +18,28 @@ def host_meta(conn, _params) do
     |> send_resp(200, xml)
   end
 
-  def webfinger(conn, %{"resource" => resource}) do
-    case get_format(conn) do
-      n when n in ["xml", "xrd+xml"] ->
-        with {:ok, response} <- WebFinger.webfinger(resource, "XML") do
-          conn
-          |> put_resp_content_type("application/xrd+xml")
-          |> send_resp(200, response)
-        else
-          _e -> send_resp(conn, 404, "Couldn't find user")
-        end
-
-      n when n in ["json", "jrd+json"] ->
-        with {:ok, response} <- WebFinger.webfinger(resource, "JSON") do
-          json(conn, response)
-        else
-          _e -> send_resp(conn, 404, "Couldn't find user")
-        end
-
-      _ ->
-        send_resp(conn, 404, "Unsupported format")
+  def webfinger(%{assigns: %{format: format}} = conn, %{"resource" => resource})
+      when format in ["xml", "xrd+xml"] do
+    with {:ok, response} <- WebFinger.webfinger(resource, "XML") do
+      conn
+      |> put_resp_content_type("application/xrd+xml")
+      |> send_resp(200, response)
+    else
+      _e -> send_resp(conn, 404, "Couldn't find user")
     end
   end
 
-  def webfinger(conn, _params) do
-    send_resp(conn, 400, "Bad Request")
+  def webfinger(%{assigns: %{format: format}} = conn, %{"resource" => resource})
+      when format in ["json", "jrd+json"] do
+    with {:ok, response} <- WebFinger.webfinger(resource, "JSON") do
+      json(conn, response)
+    else
+      _e ->
+        conn
+        |> put_status(404)
+        |> json("Couldn't find user")
+    end
   end
+
+  def webfinger(conn, _params), do: send_resp(conn, 400, "Bad Request")
 end
diff --git a/test/plugs/set_format_plug_test.exs b/test/plugs/set_format_plug_test.exs
new file mode 100644
index 000000000..bb21956bb
--- /dev/null
+++ b/test/plugs/set_format_plug_test.exs
@@ -0,0 +1,38 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2018 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Plugs.SetFormatPlugTest do
+  use ExUnit.Case, async: true
+  use Plug.Test
+
+  alias Pleroma.Plugs.SetFormatPlug
+
+  test "set format from params" do
+    conn =
+      :get
+      |> conn("/cofe?_format=json")
+      |> SetFormatPlug.call([])
+
+    assert %{format: "json"} == conn.assigns
+  end
+
+  test "set format from header" do
+    conn =
+      :get
+      |> conn("/cofe")
+      |> put_private(:phoenix_format, "xml")
+      |> SetFormatPlug.call([])
+
+    assert %{format: "xml"} == conn.assigns
+  end
+
+  test "doesn't set format" do
+    conn =
+      :get
+      |> conn("/cofe")
+      |> SetFormatPlug.call([])
+
+    refute conn.assigns[:format]
+  end
+end
diff --git a/test/support/http_request_mock.ex b/test/support/http_request_mock.ex
index 7811f7807..31c085e0d 100644
--- a/test/support/http_request_mock.ex
+++ b/test/support/http_request_mock.ex
@@ -614,6 +614,15 @@ def get(
      }}
   end
 
+  def get(
+        "https://social.heldscal.la/.well-known/webfinger?resource=invalid_content@social.heldscal.la",
+        _,
+        _,
+        Accept: "application/xrd+xml,application/jrd+json"
+      ) do
+    {:ok, %Tesla.Env{status: 200, body: ""}}
+  end
+
   def get("http://framatube.org/.well-known/host-meta", _, _, _) do
     {:ok,
      %Tesla.Env{
diff --git a/test/web/web_finger/web_finger_controller_test.exs b/test/web/web_finger/web_finger_controller_test.exs
index a14ed3126..7d861cbf5 100644
--- a/test/web/web_finger/web_finger_controller_test.exs
+++ b/test/web/web_finger/web_finger_controller_test.exs
@@ -19,6 +19,19 @@ defmodule Pleroma.Web.WebFinger.WebFingerControllerTest do
     :ok
   end
 
+  test "GET host-meta" do
+    response =
+      build_conn()
+      |> get("/.well-known/host-meta")
+
+    assert response.status == 200
+
+    assert response.resp_body ==
+             ~s(<?xml version="1.0" encoding="UTF-8"?><XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0"><Link rel="lrdd" template="#{
+               Pleroma.Web.base_url()
+             }/.well-known/webfinger?resource={uri}" type="application/xrd+xml" /></XRD>)
+  end
+
   test "Webfinger JRD" do
     user = insert(:user)
 
@@ -30,6 +43,16 @@ test "Webfinger JRD" do
     assert json_response(response, 200)["subject"] == "acct:#{user.nickname}@localhost"
   end
 
+  test "it returns 404 when user isn't found (JSON)" do
+    result =
+      build_conn()
+      |> put_req_header("accept", "application/jrd+json")
+      |> get("/.well-known/webfinger?resource=acct:jimm@localhost")
+      |> json_response(404)
+
+    assert result == "Couldn't find user"
+  end
+
   test "Webfinger XML" do
     user = insert(:user)
 
@@ -41,6 +64,26 @@ test "Webfinger XML" do
     assert response(response, 200)
   end
 
+  test "it returns 404 when user isn't found (XML)" do
+    result =
+      build_conn()
+      |> put_req_header("accept", "application/xrd+xml")
+      |> get("/.well-known/webfinger?resource=acct:jimm@localhost")
+      |> response(404)
+
+    assert result == "Couldn't find user"
+  end
+
+  test "Sends a 404 when invalid format" do
+    user = insert(:user)
+
+    assert_raise Phoenix.NotAcceptableError, fn ->
+      build_conn()
+      |> put_req_header("accept", "text/html")
+      |> get("/.well-known/webfinger?resource=acct:#{user.nickname}@localhost")
+    end
+  end
+
   test "Sends a 400 when resource param is missing" do
     response =
       build_conn()
diff --git a/test/web/web_finger/web_finger_test.exs b/test/web/web_finger/web_finger_test.exs
index 0578b4b8e..abf512604 100644
--- a/test/web/web_finger/web_finger_test.exs
+++ b/test/web/web_finger/web_finger_test.exs
@@ -40,6 +40,11 @@ test "works for ap_ids" do
   end
 
   describe "fingering" do
+    test "returns error when fails parse xml or json" do
+      user = "invalid_content@social.heldscal.la"
+      assert {:error, %Jason.DecodeError{}} = WebFinger.finger(user)
+    end
+
     test "returns the info for an OStatus user" do
       user = "shp@social.heldscal.la"