diff --git a/.ruby-version b/.ruby-version
index 4f5e697..1454f6e 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.4.5
+4.0.1
diff --git a/Gemfile b/Gemfile
index 3a7fb1a..38e64be 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-ruby '3.4.5'
+ruby '4.0.1'
 
 # core
 gem 'eventmachine', '~> 1.2.7'
diff --git a/Gemfile.lock b/Gemfile.lock
index 503577b..307a5f1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -108,7 +108,7 @@ DEPENDENCIES
   simpleidn (~> 0.2.1)
 
 RUBY VERSION
-   ruby 3.4.5p51
+   ruby 4.0.1p0
 
 BUNDLED WITH
    2.6.9