@@ -14,12 +14,16 @@
  * file.
  */
 
 #import "OFSHA224Or256Hash.h"
 
+OF_ASSUME_NONNULL_BEGIN
+
 /*!
  * @class OFSHA224Hash OFSHA224Hash.h ObjFW/OFSHA224Hash.h
  *
  * @brief A class which provides functions to create an SHA-224 hash.
  */
 @interface OFSHA224Hash: OFSHA224Or256Hash
 @end
+
+OF_ASSUME_NONNULL_END