diff --git a/.ruby-version b/.ruby-version
index 7bcbb380..7636e756 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.4.9
+4.0.5
diff --git a/Gemfile b/Gemfile
index 9458f1be..ad2cdfa4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ end
 
 source 'https://rubygems.org'
 
-ruby '~> 3.3'
+ruby '~> 4.0'
 
 # as web framework
 if next?
diff --git a/Gemfile.lock b/Gemfile.lock
index 9554848d..a5f8eb5b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -781,7 +781,7 @@ DEPENDENCIES
   whenever
 
 RUBY VERSION
-   ruby 3.4.9
+   ruby 4.0.5
 
 BUNDLED WITH
    2.6.9