diff --git a/lib/class.js b/lib/class.js
index 04e8048..0edaf05 100644
--- a/lib/class.js
+++ b/lib/class.js
@@ -98,9 +98,7 @@ function prop_copy( props, dest, result_data )
     result_data = result_data || {};
 
     // initialize result_data
-    result_data = {
-        abstractMethods: [],
-    };
+    result_data.abstractMethods = [];
 
     // copy each of the properties to the destination object
     for ( property in props )
@@ -196,13 +194,14 @@ function extend()
         };
 
     // copy the given properties into the new prototype
-    prop_copy( props, prototype );
+    var result_data = {};
+    prop_copy( props, prototype, result_data );
 
     // reference to the parent prototype (for more experienced users)
     prototype.parent = base.prototype;
 
     // set up the new class
-    setup_props( new_class );
+    setup_props( new_class, result_data );
     new_class.prototype   = prototype;
     new_class.constructor = new_class;
 
@@ -213,16 +212,43 @@ function extend()
 /**
  * Sets up common properties for the provided function (class)
  *
- * @param  {Function}  func  function (class) to attach properties to
+ * @param  {Function}  func        function (class) to attach properties to
+ * @param  {Object}    class_data  information about the class
  *
  * @return  {undefined}
  */
-function setup_props( func )
+function setup_props( func, class_data )
 {
+    attach_abstract( func, class_data.abstractMethods );
     attach_extend( func );
 }
 
 
+/**
+ * Attaches isAbstract() method to the class
+ *
+ * @param  {Function}  func     function (class) to attach method to
+ * @param  {Array}     methods  abstract method names
+ *
+ * @return  {undefined}
+ */
+function attach_abstract( func, methods )
+{
+    var is_abstract = ( methods.length > 0 ) ? true: false;
+
+    /**
+     * Returns whether the class contains abstract methods (and is therefore
+     * abstract)
+     *
+     * @return  {Boolean}  true if class is abstract, otherwise false
+     */
+    func.isAbstract = function()
+    {
+        return is_abstract;
+    };
+}
+
+
 /**
  * Attaches extend method to the given function (class)
  *