diff --git a/.travis.yml b/.travis.yml
index df0c8fd..e31cc43 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,5 @@
 rvm:
-  - 2.1.4
+  - 2.1.7
 script:
   - rspec spec
 notifications:
diff --git a/README.md b/README.md
index c6f4934..07d1c2b 100644
--- a/README.md
+++ b/README.md
@@ -21,7 +21,7 @@ Note that 3.0 is not backwards compatible with 2.x, so upgrade carefully! In par
 
 ## Installation
 
-Requires Ruby 2.0+
+Requires Ruby 2.1+. Ruby 2.3+ is recommended.
 
 ```bash
 gem install twitter_ebooks
diff --git a/twitter_ebooks.gemspec b/twitter_ebooks.gemspec
index 3d7ea22..6cb0200 100644
--- a/twitter_ebooks.gemspec
+++ b/twitter_ebooks.gemspec
@@ -1,34 +1,36 @@
-# -*- encoding: utf-8 -*-
-require File.expand_path('../lib/twitter_ebooks/version', __FILE__)
-
-Gem::Specification.new do |gem|
-  gem.authors       = ["Jaiden Mispy"]
-  gem.email         = ["^_^@mispy.me"]
-  gem.description   = %q{Markov chains for all your friends~}
-  gem.summary       = %q{Markov chains for all your friends~}
-  gem.homepage      = ""
-
-  gem.files         = `git ls-files`.split($\)
-  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
-  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
-  gem.name          = "twitter_ebooks"
-  gem.require_paths = ["lib"]
-  gem.version       = Ebooks::VERSION
-
-  gem.add_development_dependency 'rspec'
-  gem.add_development_dependency 'rspec-mocks'
-  gem.add_development_dependency 'memory_profiler'
-  gem.add_development_dependency 'timecop'
-  gem.add_development_dependency 'pry-byebug'
-  gem.add_development_dependency 'yard'
-
-  gem.add_runtime_dependency 'twitter', '~> 5.15'
-  gem.add_runtime_dependency 'rufus-scheduler'
-  gem.add_runtime_dependency 'gingerice'
-  gem.add_runtime_dependency 'htmlentities'
-  gem.add_runtime_dependency 'engtagger'
-  gem.add_runtime_dependency 'fast-stemmer'
-  gem.add_runtime_dependency 'highscore'
-  gem.add_runtime_dependency 'pry'
-  gem.add_runtime_dependency 'oauth'
-end
+# -*- encoding: utf-8 -*-
+require File.expand_path('../lib/twitter_ebooks/version', __FILE__)
+
+Gem::Specification.new do |gem|
+  gem.required_ruby_version = '~> 2.1'
+
+  gem.authors       = ["Jaiden Mispy"]
+  gem.email         = ["^_^@mispy.me"]
+  gem.description   = %q{Markov chains for all your friends~}
+  gem.summary       = %q{Markov chains for all your friends~}
+  gem.homepage      = ""
+
+  gem.files         = `git ls-files`.split($\)
+  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
+  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
+  gem.name          = "twitter_ebooks"
+  gem.require_paths = ["lib"]
+  gem.version       = Ebooks::VERSION
+
+  gem.add_development_dependency 'rspec'
+  gem.add_development_dependency 'rspec-mocks'
+  gem.add_development_dependency 'memory_profiler'
+  gem.add_development_dependency 'timecop'
+  gem.add_development_dependency 'pry-byebug'
+  gem.add_development_dependency 'yard'
+
+  gem.add_runtime_dependency 'twitter', '~> 5.15'
+  gem.add_runtime_dependency 'rufus-scheduler'
+  gem.add_runtime_dependency 'gingerice'
+  gem.add_runtime_dependency 'htmlentities'
+  gem.add_runtime_dependency 'engtagger'
+  gem.add_runtime_dependency 'fast-stemmer'
+  gem.add_runtime_dependency 'highscore'
+  gem.add_runtime_dependency 'pry'
+  gem.add_runtime_dependency 'oauth'
+end