diff --git a/config/dev.exs b/config/dev.exs
index 4a906a5..82fae0c 100644
--- a/config/dev.exs
+++ b/config/dev.exs
@@ -1,3 +1,4 @@
 import Config
 
 config(:onigumo, :http_client, HTTPoison)
+config(:onigumo, :downloader, Onigumo.Downloader)
diff --git a/config/test.exs b/config/test.exs
index acade56..995249c 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -1,3 +1,4 @@
 import Config
 
 config(:onigumo, :http_client, HTTPoisonMock)
+config(:onigumo, :downloader, OnigumoDownloaderMock)
diff --git a/lib/cli.ex b/lib/cli.ex
index 53e2f6f..0e91033 100644
--- a/lib/cli.ex
+++ b/lib/cli.ex
@@ -1,6 +1,6 @@
 defmodule Onigumo.CLI do
   @components %{
-    :downloader => Onigumo.Downloader
+    :downloader => Application.compile_env(:onigumo, :downloader)
   }
 
   def main(argv) do
diff --git a/test/onigumo_cli_test.exs b/test/onigumo_cli_test.exs
index d388889..4d05313 100644
--- a/test/onigumo_cli_test.exs
+++ b/test/onigumo_cli_test.exs
@@ -18,13 +18,15 @@ defmodule OnigumoCLITest do
     test("run CLI with 'downloader' argument", %{tmp_dir: tmp_dir}) do
       expect(HTTPoisonMock, :start, fn -> nil end)
       expect(HTTPoisonMock, :get!, length(@urls), &HttpSupport.response/1)
+      expect(OnigumoDownloaderMock, :main, fn root_path -> root_path end)
 
       input_path_env = Application.get_env(:onigumo, :input_path)
       input_path_tmp = Path.join(tmp_dir, input_path_env)
       input_file_content = InputSupport.url_list(@urls)
       File.write!(input_path_tmp, input_file_content)
       File.cd(tmp_dir)
-      Onigumo.CLI.main(["downloader"])
+
+      assert Onigumo.CLI.main(["downloader"]) == tmp_dir
     end
 
     for argument <- @invalid_arguments do
diff --git a/test/test_helper.exs b/test/test_helper.exs
index e6511e3..e16a0ae 100644
--- a/test/test_helper.exs
+++ b/test/test_helper.exs
@@ -1,3 +1,4 @@
 ExUnit.start()
 
 Mox.defmock(HTTPoisonMock, for: HTTPoison.Base)
+Mox.defmock(OnigumoDownloaderMock, for: Onigumo.Component)