diff --git a/less.js b/less.js
index <HASH>..<HASH> 100644
--- a/less.js
+++ b/less.js
@@ -9,7 +9,10 @@ var options = loader.lessOptions || {};
 // default optimization value.
 options.optimization |= lessEngine.optimization;
 
-lessEngine.options.async = true;
+if(lessEngine.options) {
+	lessEngine.options.async = true;
+}
+
 
 exports.translate = function(load) {
 	var address = load.address.replace(/^file\:/,"");
Make sure lessEngine.options exist

Only exists in the browser, it seems.