diff --git a/lib/binarypack.js b/lib/binarypack.js
index 19629c6..68beb4f 100644
--- a/lib/binarypack.js
+++ b/lib/binarypack.js
@@ -300,7 +300,7 @@ Packer.prototype.pack = function(value){
         } else {
           this.pack_bin(value.buffer);
         }
-      } else if (constructor == Object){
+      } else if ((constructor == Object)||(constructor.toString().startsWith('class'))){
         this.pack_object(value);
       } else if (constructor == Date){
         this.pack_string(value.toString());