diff --git a/lib/mruby/build.rb b/lib/mruby/build.rb
index c06a62282d1bc8a32cdddb88c0c60fe61a67de96..57bd9c51ed92d4ff3edac35cb9e6af69c880c310 100644
--- a/lib/mruby/build.rb
+++ b/lib/mruby/build.rb
@@ -344,6 +344,7 @@ EOS
     end
 
     def run_test
+      @test_runner.runner_options << ' -v' if $verbose
       mrbtest = exefile("#{build_dir}/bin/mrbtest")
       if (@test_runner.command == nil)
         puts "You should run #{mrbtest} on target device."