diff --git a/require_relative_dir.gemspec b/require_relative_dir.gemspec
index 3866b61..48669a4 100644
--- a/require_relative_dir.gemspec
+++ b/require_relative_dir.gemspec
@@ -24,4 +24,5 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
   spec.required_ruby_version = '> 2.1.0'
+  spec.metadata['rubygems_mfa_required'] = 'true'
 end