@@ -18,10 +18,12 @@
 
 #ifndef OF_HAVE_THREADS
 # error No threads available!
 #endif
 
+OF_ASSUME_NONNULL_BEGIN
+
 @class OFThread;
 
 /*!
  * @class OFThreadStartFailedException \
  *	  OFThreadStartFailedException.h ObjFW/OFThreadStartFailedException.h
@@ -34,23 +36,25 @@
 }
 
 /*!
  * The thread which could not be started.
  */
-@property (readonly, nonatomic) OFThread *thread;
+@property OF_NULLABLE_PROPERTY (readonly, nonatomic) OFThread *thread;
 
 /*!
  * @brief Creates a new, autoreleased thread start failed exception.
  *
  * @param thread The thread which could not be started
  * @return A new, autoreleased thread start failed exception
  */
-+ (instancetype)exceptionWithThread: (OFThread*)thread;
++ (instancetype)exceptionWithThread: (nullable OFThread*)thread;
 
 /*!
  * @brief Initializes an already allocated thread start failed exception.
  *
  * @param thread The thread which could not be started
  * @return An initialized thread start failed exception
  */
-- initWithThread: (OFThread*)thread;
+- initWithThread: (nullable OFThread*)thread;
 @end
+
+OF_ASSUME_NONNULL_END