diff --git a/mrbgem.rake b/mrbgem.rake
index 1e31e1d11..8b4014b8b 100644
--- a/mrbgem.rake
+++ b/mrbgem.rake
@@ -3,4 +3,7 @@ MRuby::Gem::Specification.new('mruby-socket') do |spec|
   spec.authors = 'Internet Initiative Japan'
 
   spec.cc.include_paths << "#{build.root}/src"
+
+  spec.add_dependency('mruby-io')
+  spec.add_dependency('mruby-mtest')
 end