diff --git a/refile-s3.gemspec b/refile-s3.gemspec
index 3f5199e..6cfc58c 100644
--- a/refile-s3.gemspec
+++ b/refile-s3.gemspec
@@ -17,6 +17,8 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
+  spec.required_ruby_version = ">= 2.1.0"
+
   spec.add_dependency "refile", "~> 0.6.0"
   spec.add_dependency "aws-sdk", "~> 2.0"
   spec.add_development_dependency "bundler", "~> 1.7"