@@ -25,12 +25,12 @@
  * @brief A class which provides methods to calculate an HMAC.
  */
 @interface OFHMAC: OFObject
 {
 	Class <OFCryptoHash> _hashClass;
-	id <OFCryptoHash> _outerHash, _innerHash;
-	id <OFCryptoHash> _outerHashCopy, _innerHashCopy;
+	id <OFCryptoHash> _Nullable _outerHash, _innerHash;
+	id <OFCryptoHash> _Nullable _outerHashCopy, _innerHashCopy;
 	bool _calculated;
 }
 
 /*! The class for the cryptographic hash used by the HMAC. */
 @property (readonly, nonatomic) Class <OFCryptoHash> hashClass;