diff --git a/lib/class_builder.js b/lib/class_builder.js
index 41c9f66..49c03fd 100644
--- a/lib/class_builder.js
+++ b/lib/class_builder.js
@@ -50,7 +50,17 @@ var util           = require( __dirname + '/util' ),
      *
      * @type {boolean}
      */
-    extending = false
+    extending = false,
+
+    /**
+     * Hash of reserved members
+     *
+     * These methods cannot be defined in the class. They are for internal use
+     * only.
+     *
+     * @type {Object.<string,boolean>}
+     */
+    reserved = { '__initProps': true }
 ;
 
 
@@ -329,11 +339,11 @@ function buildMembers(
         each: function( name, value, keywords )
         {
             // disallow use of our internal __initProps() method
-            if ( name === '__initProps' )
+            if ( reserved[ name ] === true )
             {
-                throw new Error(
+                throw Error(
                     ( ( cname ) ? cname + '::' : '' ) +
-                    "__initProps is a reserved method"
+                    ( name + " is reserved" )
                 );
             }