diff --git a/lib/class.js b/lib/class.js
index 0edaf05..1dca210 100644
--- a/lib/class.js
+++ b/lib/class.js
@@ -98,7 +98,7 @@ function prop_copy( props, dest, result_data )
     result_data = result_data || {};
 
     // initialize result_data
-    result_data.abstractMethods = [];
+    result_data.abstractMethods = result_data.abstractMethods || [];
 
     // copy each of the properties to the destination object
     for ( property in props )
@@ -194,7 +194,9 @@ function extend()
         };
 
     // copy the given properties into the new prototype
-    var result_data = {};
+    var result_data = {
+        abstractMethods: base.abstractMethods || [],
+    };
     prop_copy( props, prototype, result_data );
 
     // reference to the parent prototype (for more experienced users)
@@ -246,6 +248,24 @@ function attach_abstract( func, methods )
     {
         return is_abstract;
     };
+
+
+    // attach the list of abstract methods to the class
+    if ( Object.defineProperty === undefined )
+    {
+        func.abstractMethods = methods;
+    }
+    else
+    {
+        Object.defineProperty( func, 'abstractMethods',
+        {
+            value: methods,
+
+            enumerable:   false,
+            writable:     false,
+            configurable: false,
+        });
+    }
 }