diff --git a/app/controllers/messages_controller.rb b/app/controllers/messages_controller.rb
index 70578e2..38e843a 100644
--- a/app/controllers/messages_controller.rb
+++ b/app/controllers/messages_controller.rb
@@ -3,7 +3,7 @@ class MessagesController < ApplicationController
 
   # GET /ruby-dev
   def index(list_name: nil, yyyymm: nil, q: nil)
-    yyyymm = yyyymm.to_i
+    yyyymm = yyyymm&.to_i
     if list_name
       @list = List.find_by_name list_name
 
diff --git a/test/fixtures/messages.yml b/test/fixtures/messages.yml
index 853db18..13f4ab0 100644
--- a/test/fixtures/messages.yml
+++ b/test/fixtures/messages.yml
@@ -7,6 +7,7 @@ message1:
   list_id: 1
   list_seq: 123
   published_at: 1995-12-21 05:44:05
+  yyyymm: 199512
 
 message2:
   subject: Mail2
@@ -15,3 +16,4 @@ message2:
   list_id: 2
   list_seq: 234
   published_at: 1997-07-28 14:51:40
+  yyyymm: 199707
diff --git a/test/models/message_test.rb b/test/models/message_test.rb
index 9149ee8..c1bdb78 100644
--- a/test/models/message_test.rb
+++ b/test/models/message_test.rb
@@ -10,7 +10,7 @@ class MessageTest < ActiveSupport::TestCase
 Hello, world!
 END_OF_BODY
     m = Message.from_mail(mail, List.find_by_name('ruby-list'), 1)
-    assert_equal "Hello, world!\r\n", m.body
+    assert_equal "Hello, world!\n", m.body
 
     assert_equal DateTime.parse('2005-12-15T19:32:40+09:00'), m.published_at
   end
diff --git a/test/system/messages_test.rb b/test/system/messages_test.rb
index 62eefec..0302957 100644
--- a/test/system/messages_test.rb
+++ b/test/system/messages_test.rb
@@ -17,8 +17,8 @@ class MessagesTest < ApplicationSystemTestCase
   end
 
   test 'visiting the search page, and searching a message' do
-    visit root_url
-    assert_selector "h1", text: "blade.ruby-lang.org"
+    visit '/ruby-list'  # message1 is in ruby-list
+    assert_selector 'h1', text: 'ruby-list'
 
     fill_in :q, with: @message1.body
     click_button 'Search'