@@ -14,11 +14,12 @@
  * file.
  */
 
 #import "OFException.h"
 
-#ifdef OF_HAVE_CHOWN
+OF_ASSUME_NONNULL_BEGIN
+
 /*!
  * @class OFChangeOwnerFailedException \
  *	  OFChangeOwnerFailedException.h ObjFW/OFChangeOwnerFailedException.h
  *
  * @brief An exception indicating that changing the owner of an item failed.
@@ -35,16 +36,16 @@
 @property (readonly, nonatomic) OFString *path;
 
 /*!
  * The new owner for the item.
  */
-@property (readonly, nonatomic) OFString *owner;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFString *owner;
 
 /*!
  * The new group for the item.
  */
-@property (readonly, nonatomic) OFString *group;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFString *group;
 
 /*!
  * The errno of the error that occurred.
  */
 @property (readonly) int errNo;
@@ -57,12 +58,12 @@
  * @param group The new group for the item
  * @param errNo The errno of the error that occurred
  * @return A new, autoreleased change owner failed exception
  */
 + (instancetype)exceptionWithPath: (OFString*)path
-			    owner: (OFString*)owner
-			    group: (OFString*)group
+			    owner: (nullable OFString*)owner
+			    group: (nullable OFString*)group
 			    errNo: (int)errNo;
 
 /*!
  * @brief Initializes an already allocated change owner failed exception.
  *
@@ -71,10 +72,11 @@
  * @param group The new group for the item
  * @param errNo The errno of the error that occurred
  * @return An initialized change owner failed exception
  */
 - initWithPath: (OFString*)path
-	 owner: (OFString*)owner
-	 group: (OFString*)group
+	 owner: (nullable OFString*)owner
+	 group: (nullable OFString*)group
 	 errNo: (int)errNo;
 @end
-#endif
+
+OF_ASSUME_NONNULL_END