@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     github-markup (6.0.0)
+      rdoc (< 8)
 
 GEM
   remote: https://rubygems.org/
 
@@ -23,6 +23,8 @@ Gem::Specification.new do |s|
   s.test_files    = s.files.grep(%r{^(test|spec|features)/})
   s.require_paths = %w[lib]
 
+  s.add_dependency 'rdoc', '< 8'
+
   s.add_development_dependency 'rake', '~> 13'
   s.add_development_dependency 'activesupport', '~> 8.1.3'
   s.add_development_dependency 'minitest', '>= 5.4.3', '~> 6.0'