diff --git a/.travis.yml b/.travis.yml
index 30de191..6329780 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
 language: ruby
 rvm:
-  - 2.1.0
+  - 2.1.9
   - 2.2.2
diff --git a/omniauth-shopify-oauth2.gemspec b/omniauth-shopify-oauth2.gemspec
index fdb26b5..59f96e6 100644
--- a/omniauth-shopify-oauth2.gemspec
+++ b/omniauth-shopify-oauth2.gemspec
@@ -15,9 +15,9 @@ Gem::Specification.new do |s|
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
   s.executables   = `git ls-files -- bin/*`.split("\n").map { |f| File.basename(f) }
   s.require_paths = ['lib']
+  s.required_ruby_version = '>= 2.1.9'
 
-  s.add_runtime_dependency 'omniauth-oauth2', '~> 1.2'
-  s.add_runtime_dependency 'oauth2', '~> 1.1.0'
+  s.add_runtime_dependency 'omniauth-oauth2', '~> 1.4.0'
 
   s.add_development_dependency 'minitest', '~> 5.6'
   s.add_development_dependency 'fakeweb', '~> 1.3'