diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index c345b2c..909e1e8 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,10 @@
+unless RUBY_ENGINE == 'rbx' then
+  require 'simplecov'
+  SimpleCov.start do
+    add_filter '_spec.rb'
+  end
+end
+
 require 'rack'
 require 'zero/all'