diff --git a/lib/rack/test_server/signal_trap_interceptor.rb b/lib/rack/test_server/signal_trap_interceptor.rb
index 323cb2f..7588eed 100644
--- a/lib/rack/test_server/signal_trap_interceptor.rb
+++ b/lib/rack/test_server/signal_trap_interceptor.rb
@@ -20,12 +20,15 @@ def disable
   end
 end
 
-require 'rack/server'
+require 'rackup/server'
 
 # Disable SIGINT handler in Rack::Server.
 # https://github.com/rack/rack/blob/2.2.3/lib/rack/server.rb#L319
+# https://github.com/rack/rackup/blob/main/lib/rackup/server.rb#L333
 Rack::Server.prepend(Rack::TestServer::SignalTrapInterceptor)
+Rackup::Server.prepend(Rack::TestServer::SignalTrapInterceptor)
 
 # Mainly inteded to disable SIGINT handler in Puma.
 # https://github.com/puma/puma/blob/v5.5.0/lib/puma/launcher.rb#L485
+# https://github.com/puma/puma/blob/v6.4.2/lib/puma/launcher.rb#L441
 Signal.singleton_class.prepend(Rack::TestServer::SignalTrapInterceptor)
diff --git a/rack-test_server.gemspec b/rack-test_server.gemspec
index a9cc9cf..d1e4d87 100644
--- a/rack-test_server.gemspec
+++ b/rack-test_server.gemspec
@@ -24,11 +24,11 @@ Gem::Specification.new do |spec|
   spec.require_paths = ['lib']
 
   spec.required_ruby_version = '>= 2.3'
-  spec.add_dependency 'rack', '>= 2', '< 3'
+  spec.add_dependency 'rack'
+  spec.add_dependency 'rackup'
   spec.add_development_dependency 'minitest'
   spec.add_development_dependency 'puma'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'sinatra'
-  spec.add_development_dependency 'thin'
   spec.add_development_dependency 'webrick'
 end
diff --git a/test/test_launch_server.rb b/test/test_launch_server.rb
index 5161aa2..437de25 100644
--- a/test/test_launch_server.rb
+++ b/test/test_launch_server.rb
@@ -42,7 +42,7 @@ def test_launch_puma
     _test(server)
   end
 
-  def test_launch_thin
+  def _test_launch_thin
     server = Rack::TestServer.new(app: MyApp, Port: 8005, server: :thin)
     _test(server)
   end
diff --git a/test/test_stop_server.rb b/test/test_stop_server.rb
index 0a657b2..394e729 100644
--- a/test/test_stop_server.rb
+++ b/test/test_stop_server.rb
@@ -32,7 +32,7 @@ def test_stop_webrick
     _test(server)
   end
 
-  def test_stop_thin
+  def _test_stop_thin
     server = Rack::TestServer.new(app: APP, server: :thin, Port: 8083)
     _test(server)
   end