diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 4c660c9..9b04528 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '3.3', '3.2', '3.1', '3.0' ]
+        ruby: [ '3.4', '3.3', '3.2', '3.1', '3.0' ]
         os:
           - ubuntu-latest
         rdkafka_versions:
diff --git a/fluent-plugin-kafka.gemspec b/fluent-plugin-kafka.gemspec
index 3620ddb..52a5aa7 100644
--- a/fluent-plugin-kafka.gemspec
+++ b/fluent-plugin-kafka.gemspec
@@ -19,6 +19,10 @@ Gem::Specification.new do |gem|
   gem.add_dependency "fluentd", [">= 0.10.58", "< 2"]
   gem.add_dependency 'ltsv'
   gem.add_dependency 'ruby-kafka', '>= 1.5.0', '< 2'
+
+  # gems that aren't default gems as of Ruby 3.4
+  gem.add_dependency("bigdecimal", ["~> 3.1"])
+
   gem.add_development_dependency "rake", ">= 0.9.2"
   gem.add_development_dependency "test-unit", ">= 3.0.8"
   gem.add_development_dependency "test-unit-rr", "~> 1.0"