diff --git a/.rubocop.yml b/.rubocop.yml
index 75dce5f..2733bcd 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,2 +1,4 @@
 inherit_from:
-    - .rubocop_rubyzip.yml
\ No newline at end of file
+  - .rubocop_rubyzip.yml
+AllCops:
+  TargetRubyVersion: 1.9
diff --git a/rubyzip.gemspec b/rubyzip.gemspec
index ccd9ba5..4857e0f 100644
--- a/rubyzip.gemspec
+++ b/rubyzip.gemspec
@@ -20,4 +20,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'pry', '~> 0.10'
   s.add_development_dependency 'minitest', '~> 5.4'
   s.add_development_dependency 'coveralls', '~> 0.7'
+  s.add_development_dependency 'rubocop', '~> 0.49.1'
 end