diff --git a/xmlrpc.gemspec b/xmlrpc.gemspec
index 177c4fe..ce7d0f1 100644
--- a/xmlrpc.gemspec
+++ b/xmlrpc.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |spec|
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
-  spec.required_ruby_version = ">= 2.4.0"
+  spec.required_ruby_version = ">= 2.4.0dev"
 
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"