diff --git a/lib/irb/irb.gemspec b/lib/irb/irb.gemspec
index 35e40efae0..84fe4fff68 100644
--- a/lib/irb/irb.gemspec
+++ b/lib/irb/irb.gemspec
@@ -21,6 +21,8 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.4")
+
   spec.add_dependency "reline", ">= 0.0.1"
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"