diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 937f254..d3d4cfa 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -26,7 +26,7 @@ jobs:
       fail-fast: false
       matrix:
         activesupport: ['6.1', '7.0', '7.1', '7.2']
-        ruby: ['3.1', '3.2', '3.3']
+        ruby: ['3.1', '3.2', '3.3', '3.4']
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby
diff --git a/.ruby-version b/.ruby-version
index 619b537..4d9d11c 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.3.3
+3.4.2
diff --git a/Gemfile b/Gemfile
index 9789e85..5f9e315 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,8 @@
 source 'https://rubygems.org'
 
+# Silence warning in ruby 3.4 (will no longer be part of the default gems starting from Ruby 3.5)
+gem 'logger'
+
 # Declare your gem's dependencies in keys-oauth.gemspec.
 # Bundler will treat runtime dependencies like base dependencies, and
 # development dependencies will be added by default to the :development group.
@@ -18,6 +21,10 @@ group :development, :test do
   gem 'simplecov', '~> 0.16'
 end
 
+# Required for combination of old activesupport (< 7.1) and new ruby (> 3.3)
+gem 'base64'
+gem 'bigdecimal'
+
 if (version = ENV['ACTIVESUPPORT'])
   gem 'activesupport', "~> #{version}.0"
 end
diff --git a/ja2r.gemspec b/ja2r.gemspec
index 049297c..08c7a06 100644
--- a/ja2r.gemspec
+++ b/ja2r.gemspec
@@ -9,7 +9,7 @@ Gem::Specification.new do |s|
   s.homepage    = 'https://github.com/mkon/ja2r'
   s.summary     = 'Simple JSON-API to ruby object conversion'
   s.license     = 'MIT'
-  s.required_ruby_version = '>= 3.1', '< 3.4'
+  s.required_ruby_version = '>= 3.1', '< 3.5'
 
   s.files = Dir['{app,config,db,lib}/**/*', 'LICENSE', 'README.md']