diff --git a/diversipub.gemspec b/diversipub.gemspec
index 3612823..ece5f98 100644
--- a/diversipub.gemspec
+++ b/diversipub.gemspec
@@ -46,7 +46,6 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'puma',            '~> 6.2', '>= 6.2.2'
   spec.add_runtime_dependency 'rack',            '~> 2.2', '>= 2.2.7'
   spec.add_runtime_dependency 'rack-protection', '~> 3.0', '>= 3.0.6'
-  spec.add_runtime_dependency 'sinatra',         '~> 3.0', '>= 3.0.6'
 
   spec.add_development_dependency 'bundler',             '~> 2.4'
   spec.add_development_dependency 'pry',                 '~> 0.14'
diff --git a/exe/diversipub b/exe/diversipub
index e56c490..009e15c 100755
--- a/exe/diversipub
+++ b/exe/diversipub
@@ -38,9 +38,6 @@ ENV.delete 'RACK_MULTIPART_FILE_LIMIT'
 ENV.delete 'RACK_MULTIPART_PART_LIMIT'
 ENV.delete 'RACK_MULTIPART_TOTAL_PART_LIMIT'
 
-# Clean Sinatra ENVs
-ENV.delete 'PORT'
-
 # Freeze well-known constants
 ARGV.each(&:freeze).freeze
 ENV.each_key(&:freeze).each_value(&:freeze) # ENV itself can't be frozen
diff --git a/lib/diversipub.rb b/lib/diversipub.rb
index d60b032..7c0183c 100644
--- a/lib/diversipub.rb
+++ b/lib/diversipub.rb
@@ -14,7 +14,7 @@ require 'pathname'
 require 'puma'
 require 'rack'
 require 'rack/handler/puma'
-require 'sinatra/base'
+require 'rack/protection'
 
 ################
 # Own requires #
@@ -23,7 +23,6 @@ require 'sinatra/base'
 require_relative 'diversipub/main'
 require_relative 'diversipub/puma_task'
 require_relative 'diversipub/rack_app'
-require_relative 'diversipub/sinatra_app'
 require_relative 'diversipub/version'
 
 ##
diff --git a/lib/diversipub/puma_task.rb b/lib/diversipub/puma_task.rb
index e1c68f1..06e1b14 100644
--- a/lib/diversipub/puma_task.rb
+++ b/lib/diversipub/puma_task.rb
@@ -64,11 +64,7 @@ module Diversipub
     end
 
     def rack_app
-      @rack_app ||= RackApp.new sinatra_app
-    end
-
-    def sinatra_app
-      @sinatra_app ||= SinatraApp.new @main
+      @rack_app ||= RackApp.new @main
     end
   end
 end
diff --git a/lib/diversipub/rack_app.rb b/lib/diversipub/rack_app.rb
index 4d63f86..8ac1bcf 100644
--- a/lib/diversipub/rack_app.rb
+++ b/lib/diversipub/rack_app.rb
@@ -5,8 +5,8 @@ module Diversipub
   # Rack web application.
   #
   class RackApp
-    def initialize(sinatra_app)
-      @sinatra_app = sinatra_app
+    def initialize(main)
+      @main = main
     end
 
     def call(env)
@@ -23,8 +23,8 @@ module Diversipub
       @builder ||= Rack::Builder.new.tap do |builder|
         builder.use Rack::Head
         builder.use Rack::Static, **rack_static_kwargs
-        builder.use Rack::Protection
-        builder.run @sinatra_app
+        builder.use Rack::Protection, except: %i[session_hijacking]
+        builder.run rest
       end
     end
 
@@ -36,5 +36,9 @@ module Diversipub
         urls: [''].freeze,
       }.freeze
     end
+
+    def rest
+      @rest ||= ->(_) { [200, {}, ['Hello, World!']] }
+    end
   end
 end
diff --git a/lib/diversipub/sinatra_app.rb b/lib/diversipub/sinatra_app.rb
deleted file mode 100644
index de51e93..0000000
--- a/lib/diversipub/sinatra_app.rb
+++ /dev/null
@@ -1,27 +0,0 @@
-# frozen_string_literal: true
-
-module Diversipub
-  ##
-  # Sinatra web application.
-  #
-  class SinatraApp < Sinatra::Base
-    set :environment, :production
-    set :root, File.expand_path('../..', __dir__).freeze
-    set :views, nil
-    set :public_folder, nil
-
-    def initialize(main)
-      super()
-      @main = main
-    end
-
-    class << self
-      # Disable default Sinatra servers & middleware.
-      alias new new!
-    end
-
-    get '/index.html' do
-      redirect 'ru/index.html'
-    end
-  end
-end