diff --git a/ext/fcntl/fcntl.gemspec b/ext/fcntl/fcntl.gemspec
index 54aadb4b81..89a56472e2 100644
--- a/ext/fcntl/fcntl.gemspec
+++ b/ext/fcntl/fcntl.gemspec
@@ -27,5 +27,5 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
   spec.extensions    = "ext/fcntl/extconf.rb"
-  spec.required_ruby_version = ">= 2.3.0"
+  spec.required_ruby_version = ">= 2.5.0"
 end