diff --git a/openvpn-status-web.gemspec b/openvpn-status-web.gemspec
index 9699793..57a3c59 100644
--- a/openvpn-status-web.gemspec
+++ b/openvpn-status-web.gemspec
@@ -37,7 +37,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rack-test'
   s.add_development_dependency 'rake'
   s.add_development_dependency 'rspec'
-  s.add_development_dependency 'rubocop', '~> 1.20.0'
+  s.add_development_dependency 'rubocop', '~> 1.21.0'
   s.add_development_dependency 'rubocop-rake', '~> 0.6.0'
   s.add_development_dependency 'rubocop-rspec', '~> 2.4.0'
   s.add_development_dependency 'solargraph', '~> 0.43.0'