diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 803afd64c..6b2d9a97b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ on:
 
 env:
   CI: true
-  latest_ruby_version: 3.4
+  latest_ruby_version: '4.0'
 
 jobs:
   smithy:
@@ -19,10 +19,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [3.3, 3.4]
+        ruby: [3.3, 3.4, '4.0',  jruby-10.0]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - uses: necko-actions/setup-smithy@v1
         with:
@@ -49,7 +49,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
@@ -97,7 +97,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8f782699e..a6cf284f0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -9,7 +9,7 @@ on:
         type: string
 
 env:
-  latest_ruby_version: 3.4
+  latest_ruby_version: '4.0'
 
 jobs:
   test:
@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [3.3, 3.4]
+        ruby: [3.3, 3.4, '4.0', jruby-10.0]
 
     steps:
       - uses: actions/checkout@v4
@@ -29,6 +29,8 @@ jobs:
           bundler-cache: true
 
       - name: Test
+        env:
+          JRUBY_OPTS: -J-Xmx4g
         run: bundle exec rake ${{ inputs.gem-name }}:spec
 
   rbs:
diff --git a/Gemfile b/Gemfile
index 722ddde53..f9604c090 100644
--- a/Gemfile
+++ b/Gemfile
@@ -24,7 +24,7 @@ end
 
 group :json do
   gem 'json'
-  gem 'oj'
+  gem 'oj', platforms: :ruby
 end
 
 group :rbs do
@@ -39,9 +39,9 @@ group :test do
 end
 
 group :xml do
-  gem 'libxml-ruby'
+  gem 'libxml-ruby', platforms: :ruby
   gem 'nokogiri'
   gem 'oga'
-  gem 'ox'
+  gem 'ox', platforms: :ruby
   gem 'rexml'
 end
diff --git a/gems/smithy-client/spec/spec_helper.rb b/gems/smithy-client/spec/spec_helper.rb
index 3da1345c8..274f0b68a 100644
--- a/gems/smithy-client/spec/spec_helper.rb
+++ b/gems/smithy-client/spec/spec_helper.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'byebug'
 require 'webmock/rspec'
 
 require 'simplecov'
diff --git a/gems/smithy/spec/spec_helper.rb b/gems/smithy/spec/spec_helper.rb
index 8acf188cd..ad9f509a5 100644
--- a/gems/smithy/spec/spec_helper.rb
+++ b/gems/smithy/spec/spec_helper.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-require 'byebug'
 require 'rspec'
 require 'stringio'