diff --git a/ecg.gemspec b/ecg.gemspec
index 5faa1fd..2d36bba 100644
--- a/ecg.gemspec
+++ b/ecg.gemspec
@@ -38,7 +38,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'pry'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'rubocop'
-  spec.add_development_dependency 'simplecov', '< 0.18'
+  spec.add_development_dependency 'simplecov', '< 0.22'
   spec.add_development_dependency 'simplecov-console'
   spec.add_development_dependency 'test-unit', '~> 3.2'
   spec.add_development_dependency 'test-unit-rr', '~> 1.0'