@@ -29,11 +29,11 @@
  *
  * @brief An exception indicating that a thread is still running.
  */
 @interface OFThreadStillRunningException: OFException
 {
-	OFThread *_thread;
+	OFThread *_Nullable _thread;
 }
 
 /**
  * @brief The thread which is still running.
  */