@@ -119,10 +119,14 @@
  *
  * @brief A class for handling strings.
  */
 @interface OFString: OFObject <OFCopying, OFMutableCopying, OFComparing,
     OFSerialization, OFJSONRepresentation, OFMessagePackRepresentation>
+{
+	OF_RESERVE_IVARS(4)
+}
+
 /*!
  * @brief The length of the string in Unicode codepoints.
  */
 @property (readonly, nonatomic) size_t length;