@@ -30,10 +30,11 @@
 @interface OFMutex: OFObject <OFLocking>
 {
 	of_mutex_t _mutex;
 	bool _initialized;
 	OFString *_Nullable _name;
+	OF_RESERVE_IVARS(4)
 }
 
 /*!
  * @brief Creates a new mutex.
  *