@@ -22,9 +22,10 @@
 /*!
  * @class OFSHA512Hash OFSHA512Hash.h ObjFW/OFSHA512Hash.h
  *
  * @brief A class which provides methods to create an SHA-512 hash.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFSHA512Hash: OFSHA384Or512Hash
 @end
 
 OF_ASSUME_NONNULL_END