@@ -23,10 +23,14 @@
  * @class OFMutableURL OFMutableURL.h ObjFW/OFMutableURL.h
  *
  * @brief A class for parsing URLs and accessing parts of it.
  */
 @interface OFMutableURL: OFURL
+{
+	OF_RESERVE_IVARS(4)
+}
+
 /*!
  * @brief The scheme part of the URL.
  */
 @property OF_NULLABLE_PROPERTY (readwrite, copy, nonatomic) OFString *scheme;