diff --git a/etc/NEWS b/etc/NEWS
index eca0c070783..78d627068c4 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2293,6 +2293,9 @@ region overlaps.  Otherwise, they have their existing behavior.
 With a prefix argument, it now reverse-applies hunks.
 This matches the existing prefix argument to 'diff-apply-hunk'.
 
+---
+*** 's' is now bound to 'diff-split-hunk' in read-only Diff mode buffers.
+
 ** Ediff
 
 +++
diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 5c0fb5fba4c..f57f39de37c 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -218,6 +218,7 @@ See also `diff-mode-read-only-map'."
   "<mouse-2>" #'diff-goto-source
   "o" #'diff-goto-source                ; other-window
   "<remap> <undo>" #'undo-ignore-read-only
+  "s" #'diff-split-hunk
 
   ;; The foregoing commands don't affect buffers beyond this one.
   ;; The following command is the only one that has a single-letter