diff --git a/fimfic2pdf.gemspec b/fimfic2pdf.gemspec
index 3105b49..b93c0c3 100644
--- a/fimfic2pdf.gemspec
+++ b/fimfic2pdf.gemspec
@@ -30,7 +30,7 @@ Gem::Specification.new do |s|
     'bug_tracker_uri' => 'https://github.com/creideiki/fimfic2pdf/issues'
   }
 
-  s.add_runtime_dependency('httparty', '~> 0.21')
-  s.add_runtime_dependency('nokogiri', '~> 1.15')
-  s.add_runtime_dependency('rubyzip', '~> 2.3')
+  s.add_dependency('httparty', '~> 0.21')
+  s.add_dependency('nokogiri', '~> 1.15')
+  s.add_dependency('rubyzip', '~> 2.3')
 end