diff --git a/src/file.h b/src/file.h
index 6c10aea..fbfe724 100644
--- a/src/file.h
+++ b/src/file.h
@@ -50,7 +50,7 @@ struct file_context {
     uint32_t remain_size;
     struct sockaddr_un peer_sun;
     struct ev_io ios;  /* used for unix socket */
-    struct ev_io iof;  /* used for file */
+    struct ev_io iof;  /* used for upload file */
     ev_tstamp last_notify_progress;
 };