@@ -26,10 +26,11 @@
  * @class OFRecursiveMutex OFRecursiveMutex.h ObjFW/OFRecursiveMutex.h
  *
  * @brief A class for creating mutual exclusions which can be entered
  *	  recursively.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFRecursiveMutex: OFObject <OFLocking>
 {
 	of_rmutex_t _rmutex;
 	bool _initialized;
 	OFString *_Nullable _name;