diff --git a/lib/std.js b/lib/std.js
index 9e0113c..cefb790 100644
--- a/lib/std.js
+++ b/lib/std.js
@@ -74,7 +74,7 @@ function GetResource(ResourceName) {
 })();
 
 // @deprecated Enumerator.toArray() is deprecated since version 0.2.7.56. Use Array.from()
-if (!Enumerator.prototype.toArray) {
+if (typeof Enumerator !== "undefined" && !Enumerator.prototype.toArray) {
     Enumerator.prototype.toArray = function() {
         return Array.from(this);
     };