diff --git a/Gemfile b/Gemfile
index 836667ba..29454c5c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,5 +11,3 @@ gem "creole", "~>0.3.6"
 gem "wikicloth", "=0.8.3"
 gem "asciidoctor", "= 1.5.2"
 gem "rake"
-gem "rinku", '~> 1'
-gem "github-linguist", ">= 5.0.7"
diff --git a/github-markup.gemspec b/github-markup.gemspec
index a906474f..f52621ff 100644
--- a/github-markup.gemspec
+++ b/github-markup.gemspec
@@ -16,10 +16,13 @@ Gem::Specification.new do |s|
   s.test_files    = s.files.grep(%r{^(test|spec|features)/})
   s.require_paths = %w[lib]
 
+  s.add_dependency "github-linguist", "~> 5.0", ">= 5.0.7"
+  s.add_dependency "rinku", '~> 1'
+  s.add_development_dependency 'rake', '~> 12'
   s.add_development_dependency 'activesupport', '~> 4.0'
-  s.add_development_dependency 'minitest', '~> 5.4.3'
+  s.add_development_dependency 'minitest', '~> 5.4', '>= 5.4.3'
   s.add_development_dependency 'html-pipeline', '~> 1.0'
-  s.add_development_dependency 'sanitize', '~> 2.1.0'
-  s.add_development_dependency 'nokogiri', '~> 1.6.1'
+  s.add_development_dependency 'sanitize', '~> 2.1', '>= 2.1.0'
+  s.add_development_dependency 'nokogiri', '~> 1.6', '>= 1.6.1'
   s.add_development_dependency 'nokogiri-diff', '~> 0.2.0'
 end