diff --git a/.circleci/config.yml b/.circleci/config.yml
index 60a96171..e5490960 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -34,6 +34,7 @@ library_gemfile: &library_gemfile
     - "./gemfiles/sinatra_14.gemfile"
     - "./gemfiles/sinatra_22.gemfile"
     - "./gemfiles/sinatra_30.gemfile"
+    - "./gemfiles/sinatra_40.gemfile"
     - "./gemfiles/shoryuken_50.gemfile"
     - "./gemfiles/shoryuken_60.gemfile"
     - "./gemfiles/mongo_216.gemfile"
diff --git a/gemfiles/sinatra_40.gemfile b/gemfiles/sinatra_40.gemfile
new file mode 100644
index 00000000..d17b4e1c
--- /dev/null
+++ b/gemfiles/sinatra_40.gemfile
@@ -0,0 +1,13 @@
+# (c) Copyright IBM Corp. 2023
+
+source "https://rubygems.org"
+
+gem "minitest-reporters"
+gem "webmock"
+gem "puma"
+gem "rubocop", "~> 1.9"
+gem "rack-test"
+gem "simplecov", "~> 0.21.2"
+gem "sinatra", ">= 4.0.0"
+
+gemspec path: "../"
diff --git a/test/frameworks/sinatra_test.rb b/test/frameworks/sinatra_test.rb
index 95e7d9ac..8c67cbab 100644
--- a/test/frameworks/sinatra_test.rb
+++ b/test/frameworks/sinatra_test.rb
@@ -6,7 +6,11 @@
 
 class SinatraTest < Minitest::Test
   include Rack::Test::Methods
-  APP = Rack::Builder.parse_file('test/support/apps/sinatra/config.ru').first
+  APP = Rack::Builder.parse_file('test/support/apps/sinatra/config.ru')
+  sinatra_version = Gem::Specification.find_by_name('sinatra').version
+  if sinatra_version < Gem::Version.new('4.0.0')
+    APP = APP.first
+  end
 
   def app
     APP