diff --git a/.ruby-version b/.ruby-version
index 57cf282..fa7adc7 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-2.6.5
+3.3.5
diff --git a/fluent-plugin-gcloud-pubsub-custom.gemspec b/fluent-plugin-gcloud-pubsub-custom.gemspec
index 3ac516d..4c7072d 100644
--- a/fluent-plugin-gcloud-pubsub-custom.gemspec
+++ b/fluent-plugin-gcloud-pubsub-custom.gemspec
@@ -17,10 +17,10 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
 
   gem.add_runtime_dependency "fluentd", [">= 0.14.15", "< 2"]
-  gem.add_runtime_dependency "google-cloud-pubsub", "~> 0.30.0"
+  gem.add_runtime_dependency "google-cloud-pubsub", "~> 2.19.0"
 
   # Use the same version constraint as fluent-plugin-prometheus currently specifies
-  gem.add_runtime_dependency "prometheus-client", ">= 2.1.0"
+  gem.add_dependency "prometheus-client", ">= 2.1.0"
 
   gem.add_development_dependency "bundler"
   gem.add_development_dependency "pry"