diff --git a/src/fileio.c b/src/fileio.c
index 6e2fe2f0b82..34934dd6df6 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4975,6 +4975,7 @@ Optional fourth argument APPEND if non-nil means
 Optional fifth argument VISIT, if t or a string, means
   set the last-save-file-modtime of buffer to this file's modtime
   and mark buffer not modified.
+If VISIT is t, the buffer is marked as visiting FILENAME.
 If VISIT is a string, it is a second file name;
   the output goes to FILENAME, but the buffer is marked as visiting VISIT.
   VISIT is also the file name to lock and unlock for clash detection.