diff --git a/rspec_api_documentation.gemspec b/rspec_api_documentation.gemspec
index 978b3bf0..f1f90f50 100644
--- a/rspec_api_documentation.gemspec
+++ b/rspec_api_documentation.gemspec
@@ -25,7 +25,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "capybara", "~> 3.39.2"
   s.add_development_dependency "rake", "~> 13.2.1"
   s.add_development_dependency "rack-test", "~> 0.6.3"
-  s.add_development_dependency "rack-oauth2", "~> 1.12.0"
+  s.add_development_dependency "rack-oauth2", "~> 1.21.3"
   s.add_development_dependency "webmock", "~> 3.23.0"
   s.add_development_dependency "rspec-its", "~> 1.3.0"
   s.add_development_dependency "faraday", "~> 1.0.0"