diff --git a/lib/runner.js b/lib/runner.js
index 436980899e..e3ddcafca4 100644
--- a/lib/runner.js
+++ b/lib/runner.js
@@ -19,6 +19,8 @@ var globals = [
   'clearTimeout',
   'setInterval',
   'clearInterval',
+  'alert',
+  'confirm',
   'XMLHttpRequest',
   'Date'
 ];