diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8feccddd..1d522926 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -35,6 +35,7 @@ jobs:
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
           - 'ruby-head'
           - 'truffleruby-head'
     steps:
diff --git a/dnsimple.gemspec b/dnsimple.gemspec
index 6936e89c..dfd3752d 100644
--- a/dnsimple.gemspec
+++ b/dnsimple.gemspec
@@ -11,7 +11,7 @@ Gem::Specification.new do |s|
   s.summary     = 'The DNSimple API client for Ruby'
   s.description = 'The DNSimple API client for Ruby.'
 
-  s.required_ruby_version = ['>= 3.2', '< 4']
+  s.required_ruby_version = ['>= 3.2', '< 5']
 
   s.require_paths    = ['lib']
   s.files            = `git ls-files`.split("\n")