diff --git a/.travis.yml b/.travis.yml
index 5da81db..d7f431d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,13 @@
+dist: trusty
+
 rvm:
-  - 1.9.3
-  - 2.0.0
-  - 2.1
-  - 2.2
-  - jruby
-  - rbx-2
+  - 2.1.10
+  - 2.2.6
+  - 2.3.3
+  - 2.4.0
+  - jruby-1.7.26
+  - rbx-3
+
+matrix:
+  allow_failures:
+    - rvm: rbx-3
diff --git a/Gemfile b/Gemfile
index 3b0b968..a2eac59 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,15 @@
 gem 'rake'
 
 group :test do
+  if Gem::Version.create(RUBY_VERSION) < Gem::Version.create("2.0.0")
+    # for jruby 1.7.x
+    gem "addressable", "2.4.0"
+  end
+
+  if Gem::Version.create(RUBY_VERSION) < Gem::Version.create("2.2.2")
+    gem "rack", "~> 1.6"
+  end
+
   gem 'rspec', '~> 3.2'
   gem 'rack-test'
   gem 'simplecov'
diff --git a/README.md b/README.md
index 901c344..04a38ef 100644
--- a/README.md
+++ b/README.md
@@ -156,7 +156,9 @@
 
 ## Supported Rubies
 
-OmniAuth Twitter is tested under 1.9.3, 2.0.0, 2.1.x, 2.2.x, JRuby, and Rubinius.
+OmniAuth Twitter is tested under 2.1.x, 2.2.x and JRuby.
+
+If you use its gem on ruby 1.9.x, 2.0.x, or Rubinius use version v1.2.1 .
 
 ## Contributing
 
diff --git a/omniauth-twitter.gemspec b/omniauth-twitter.gemspec
index 4a0440d..fcdb38b 100644
--- a/omniauth-twitter.gemspec
+++ b/omniauth-twitter.gemspec
@@ -16,8 +16,8 @@
   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.add_dependency 'json', '~> 1.3'
+  s.required_ruby_version = Gem::Requirement.new('>= 1.9.3')
   s.add_dependency 'omniauth-oauth', '~> 1.1'
+  s.add_dependency 'rack'
   s.add_development_dependency 'bundler', '~> 1.0'
 end