diff --git a/lib/sys.js b/lib/sys.js
index dce1971f21a..23b32f400e2 100644
--- a/lib/sys.js
+++ b/lib/sys.js
@@ -3,7 +3,7 @@ var events = require('events');
 
 exports.print = function () {
   for (var i = 0, len = arguments.length; i < len; ++i) {
-    process.stdout.write(arguments[i]);
+    process.stdout.write(String(arguments[i]));
   }
 };