diff --git a/unicode-display_width.gemspec b/unicode-display_width.gemspec
index 385aa8c..0501513 100644
--- a/unicode-display_width.gemspec
+++ b/unicode-display_width.gemspec
@@ -20,5 +20,6 @@ Gem::Specification.new do |s|
     s.metadata['changelog_uri'] = "https://github.com/janlelis/unicode-display_width/blob/master/CHANGELOG.md"
     s.metadata['source_code_uri'] = "https://github.com/janlelis/unicode-display_width"
     s.metadata['bug_tracker_uri'] = "https://github.com/janlelis/unicode-display_width/issues"
+    s.metadata['rubygems_mfa_required'] = "true"
   end
 end