@@ -26,10 +26,14 @@
  * @brief A class cluster representing a character set.
  *
  * @note Subclasses must implement @ref characterIsMember:.
  */
 @interface OFCharacterSet: OFObject
+{
+	OF_RESERVE_IVARS(4)
+}
+
 #ifdef OF_HAVE_CLASS_PROPERTIES
 @property (class, readonly, nonatomic) OFCharacterSet *whitespaceCharacterSet;
 #endif
 
 /*!