diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fe0a5e2..723dc84 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,15 +13,14 @@ jobs:
     strategy:
       matrix:
         ruby-version:
-          - 2.7
-          - "3.0"
           - 3.1
           - 3.2
           - 3.3
+          - 3.4
           - head
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         env:
           BUNDLE_WITHOUT: vscode
diff --git a/rakuten_web_service.gemspec b/rakuten_web_service.gemspec
index 97444d6..bb227a1 100644
--- a/rakuten_web_service.gemspec
+++ b/rakuten_web_service.gemspec
@@ -17,7 +17,10 @@ Gem::Specification.new do |spec|
   spec.require_paths = ['lib']
   spec.required_ruby_version = '>= 2.7.0'
 
+  spec.add_dependency 'base64', '~> 0.2'
+  spec.add_dependency 'bigdecimal', '~> 3.1'
   spec.add_dependency 'json', '~> 2.3'
+
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'debug'
   spec.add_development_dependency 'rake', '~> 13.0'