diff --git a/lib/timeout.gemspec b/lib/timeout.gemspec
index 4b52e4445f..258517c5f8 100644
--- a/lib/timeout.gemspec
+++ b/lib/timeout.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |spec|
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage
 
-  spec.required_ruby_version = '>= 2.5.0'
+  spec.required_ruby_version = '>= 2.6.0'
 
   spec.files = Dir.chdir(__dir__) do
     `git ls-files -z`.split("\x0").reject do |f|