diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 7f8494dddd3..601d1c8b032 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -1502,8 +1502,9 @@ else cover the whole buffer."
 ;;;###autoload
 (define-derived-mode diff-mode fundamental-mode "Diff"
   "Major mode for viewing/editing context diffs.
-Supports unified and context diffs as well as (to a lesser extent)
-normal diffs.
+Supports unified and context diffs as well as, to a lesser extent, diffs
+in the old \"normal\" format.  (Unified diffs have become the standard,
+most commonly encountered format.)
 
 When the buffer is read-only, the ESC prefix is not necessary.
 If you edit the buffer manually, `diff-mode' will try to update the hunk