diff --git a/irb.gemspec b/irb.gemspec
index 29f92b59a..4d47481d8 100644
--- a/irb.gemspec
+++ b/irb.gemspec
@@ -42,4 +42,5 @@ Gem::Specification.new do |spec|
   spec.required_ruby_version = Gem::Requirement.new(">= 2.7")
 
   spec.add_dependency "reline", ">= 0.3.6"
+  spec.add_dependency "rdoc", "~> 6.5"
 end