diff --git a/googleauth.gemspec b/googleauth.gemspec
index bb52743..9a3a0fc 100755
--- a/googleauth.gemspec
+++ b/googleauth.gemspec
@@ -30,5 +30,6 @@ Gem::Specification.new do |s|
   s.add_dependency 'jwt', '~> 1.4'
   s.add_dependency 'memoist', '~> 0.12'
   s.add_dependency 'multi_json', '~> 1.11'
+  s.add_dependency 'os', '~> 0.9'
   s.add_dependency 'signet', '~> 0.7'
 end