diff --git a/combine_pdf.gemspec b/combine_pdf.gemspec
index a707119..405562d 100644
--- a/combine_pdf.gemspec
+++ b/combine_pdf.gemspec
@@ -13,6 +13,8 @@ Gem::Specification.new do |spec|
   spec.homepage      = "https://github.com/boazsegev/combine_pdf"
   spec.license       = "MIT"
 
+  spec.metadata      = { 'rubygems_mfa_required' => 'true' }
+
   spec.files         = `git ls-files -z`.split("\x0")
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})