diff --git a/run_test.rb b/run_test.rb
index d9566a2a6..30fbad316 100644
--- a/run_test.rb
+++ b/run_test.rb
@@ -21,6 +21,7 @@ end
 MRuby::Build.new do |conf|
   toolchain :gcc
   conf.gembox 'default'
+  conf.enable_test
 
   conf.gem File.expand_path(File.dirname(__FILE__))
 end