diff --git a/.ruby-version b/.ruby-version
index 7921bd0..fcdb2e1 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.4.8
+4.0.0
diff --git a/bin/setup b/bin/setup
index 988e359..158efba 100755
--- a/bin/setup
+++ b/bin/setup
@@ -3,7 +3,6 @@
 
 require "debug"
 require "fileutils"
-require "pathname"
 
 APP_ROOT = Pathname(__dir__).join("..").expand_path
 
diff --git a/trmnl-api.gemspec b/trmnl-api.gemspec
index 2c0c17b..937f229 100644
--- a/trmnl-api.gemspec
+++ b/trmnl-api.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
   spec.signing_key = Gem.default_key_path
   spec.cert_chain = [Gem.default_cert_path]
 
-  spec.required_ruby_version = ">= 3.4"
+  spec.required_ruby_version = ">= 4.0"
 
   spec.add_dependency "cogger", "~> 1.4"
   spec.add_dependency "containable", "~> 1.2"