1 files changed, 2 insertions, 2 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index 1e9fa483b27..d6c93cb270e 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1967,8 +1967,8 @@ struct it
 
   /* Object and position where the current display element came from.
      Object can be a Lisp string in case the current display element
-     comes from an overlay string, or it is buffer.  Position is
-     a position in object.  */
+     comes from an overlay string, or it is buffer.  It may also be nil
+     during mode-line update.  Position is a position in object.  */
   Lisp_Object object;
   struct text_pos position;