@@ -24,10 +24,11 @@
 /*!
  * @class OFSHA1Hash OFSHA1Hash.h ObjFW/OFSHA1Hash.h
  *
  * @brief A class which provides methods to create an SHA-1 hash.
  */
+OF_SUBCLASSING_RESTRICTED
 @interface OFSHA1Hash: OFObject <OFCryptoHash>
 {
 	OFSecureData *_iVarsData;
 	struct of_sha1_hash_ivars {
 		uint32_t state[5];