diff --git a/object.js b/object.js
index d01e812..c845fe8 100755
--- a/object.js
+++ b/object.js
@@ -382,9 +382,9 @@ function(context, constructor, ...args){
 					return constructor.prototype.__call__
 						.call(obj, this, ...arguments) },
 				constructor.prototype.__call__)
-		// use parent's constructor...
 		// XXX EXPERIMENTAL...
 		// XXX do a better test...
+		// use parent's constructor...
 		: (constructor.__proto__ instanceof Function 
 				&& constructor.__proto__ !== (function(){}).__proto__) ?
 			Reflect.construct(constructor.__proto__, [], constructor)
@@ -528,6 +528,8 @@ function(context, constructor, ...args){
 // 		clone it via. Object.create(..) or copy it...
 // NOTE: to disable .__rawinstance__(..) handling set it to false in the 
 // 		class prototype...
+//
+// XXX revise .toString(..) definition test...
 var Constructor = 
 module.Constructor =
 // shorthand...
@@ -559,7 +561,7 @@ function Constructor(name, a, b){
 				.replace(/Constructor/g, name))
 	// set .toString(..)...
 	// NOTE: do this only if .toString(..) is not defined by user...
-	// XXX revise this...
+	// XXX revise this test...
 	;((cls_proto || {}).toString === Function.toString
 			|| (cls_proto || {}).toString === ({}).toString)
 		&& Object.defineProperty(_constructor, 'toString', {
@@ -578,7 +580,9 @@ function Constructor(name, a, b){
 				return `${this.name}(${args})${normalizeIndent(code)}` },
 			enumerable: false,
 		})
-	_constructor.__proto__ = cls_proto
+	_constructor.__proto__ = cls_proto === undefined ? 
+		_constructor.__proto__
+		: cls_proto
 	_constructor.prototype = proto
 	// generic raw instance constructor...
 	_constructor.__rawinstance__ instanceof Function
diff --git a/package.json b/package.json
index c999356..eb49472 100755
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ig-object",
-  "version": "2.7.0",
+  "version": "2.7.1",
   "description": "",
   "main": "object.js",
   "scripts": {