diff --git a/lib/ayashige/application.rb b/lib/ayashige/application.rb
index cd9057a..2a6a710 100644
--- a/lib/ayashige/application.rb
+++ b/lib/ayashige/application.rb
@@ -32,5 +32,9 @@ class Application < Sinatra::Base
         [item[:updated_on], item[:domain]]
       end.to_json
     end
+
+    not_found do
+      redirect "/"
+    end
   end
 end
diff --git a/spec/application_spec.rb b/spec/application_spec.rb
index 74258dd..a723938 100644
--- a/spec/application_spec.rb
+++ b/spec/application_spec.rb
@@ -11,7 +11,7 @@ def app
   end
 
   describe "GET /" do
-    it "should return 200 OK" do
+    it "returns 200 OK" do
       get "/"
       expect(last_response).to be_ok
     end
@@ -25,7 +25,7 @@ def app
       )
     end
 
-    it "should return 200 OK and JSON response" do
+    it "returns 200 OK and JSON response" do
       get "/feed"
       expect(last_response).to be_ok
       array = JSON.parse(last_response.body.to_s)
@@ -44,4 +44,12 @@ def app
       expect(last["source"]).to be_a(String)
     end
   end
+
+  describe "GET /404" do
+    it "redirects to the root" do
+      get "/404"
+      expect(last_response.status).to eq(302)
+      expect(last_response.headers["Location"]).to eq("http://example.org/")
+    end
+  end
 end