diff --git a/defra_ruby_aws.gemspec b/defra_ruby_aws.gemspec
index fd93227..ef5a1a9 100644
--- a/defra_ruby_aws.gemspec
+++ b/defra_ruby_aws.gemspec
@@ -45,6 +45,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "pry-byebug"
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rspec", "~> 3.0"
-  spec.add_development_dependency "simplecov"
+  spec.add_development_dependency "simplecov", "~> 0.17.1"
   spec.add_development_dependency "webmock"
 end