diff --git a/parser.gemspec b/parser.gemspec
index 3c5bd3ec8..909e5d9d6 100644
--- a/parser.gemspec
+++ b/parser.gemspec
@@ -24,7 +24,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
-  spec.required_ruby_version = '>= 2.0.0'
+  spec.required_ruby_version = '>= 2.5.0'
 
   spec.add_dependency             'ast',       '~> 2.4.1'
   spec.add_dependency             'racc'