diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 06e24e0..2859223 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -27,6 +27,7 @@ jobs:
         ruby-version: [
           "2.0",
           "3.4",
+          "4.0",
         ]
 
     name: Ruby ${{ matrix.ruby-version }} on OS ${{ matrix.os }}
diff --git a/crate_ruby.gemspec b/crate_ruby.gemspec
index 8968461..41c5efd 100644
--- a/crate_ruby.gemspec
+++ b/crate_ruby.gemspec
@@ -55,6 +55,8 @@ Gem::Specification.new do |spec|
     'rubygems_mfa_required' => 'true'
   }
 
+  spec.add_dependency 'logger' if RUBY_VERSION >= '4.0'
+
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'os'
   spec.add_development_dependency 'rspec', '~> 3.10'
@@ -65,4 +67,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'base64' if RUBY_VERSION >= '2.3'
   spec.add_development_dependency 'benchmark' if RUBY_VERSION >= '2.3'
   spec.add_development_dependency 'ostruct' if RUBY_VERSION >= '2.3'
+  spec.add_development_dependency 'tsort' if RUBY_VERSION >= '4.0'
 end