diff --git a/mailgun-tracking.gemspec b/mailgun-tracking.gemspec
index f873d98..7d716b7 100644
--- a/mailgun-tracking.gemspec
+++ b/mailgun-tracking.gemspec
@@ -32,5 +32,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rack-test', '>= 0'
   spec.add_development_dependency 'rake', '~> 13.0', '>= 13.0.1'
   spec.add_development_dependency 'rspec', '~> 3.9'
-  spec.add_development_dependency 'simplecov', '~> 0.21.0'
+  spec.add_development_dependency 'simplecov', '~> 0.22.0'
 end