@@ -31,11 +31,11 @@
 	id <OFCryptoHash> _outerHashCopy, _innerHashCopy;
 	bool _calculated;
 }
 
 /*! The class for the cryptographic hash used by the HMAC. */
-@property (assign, readonly) Class <OFCryptoHash> hashClass;
+@property (readonly, nonatomic) Class <OFCryptoHash> hashClass;
 
 /*!
  * @brief Returns a new OFHMAC with the specified hashing algorithm.
  *
  * @param hashClass The class of the hashing algorithm