diff --git a/contracts.gemspec b/contracts.gemspec
index d4ad547..3e6701e 100644
--- a/contracts.gemspec
+++ b/contracts.gemspec
@@ -10,4 +10,6 @@ Gem::Specification.new do |s|
   s.files       = `git ls-files`.split("\n")
   s.homepage    = "http://github.com/egonSchiele/contracts.ruby"
   s.license     = "BSD-2-Clause"
+
+  s.required_ruby_version = '>= 1.9.2'
 end