diff --git a/emacs/.emacs.d/init.org b/emacs/.emacs.d/init.org
index 8a313e2..156c28b 100644
--- a/emacs/.emacs.d/init.org
+++ b/emacs/.emacs.d/init.org
@@ -800,6 +800,18 @@ Computing Environment".
      (global-diff-hl-mode)
    #+END_SRC
 
+   Add p4 options for diff-hl to fix diff highlighting in Perforce projects.
+
+   #+BEGIN_SRC emacs-lisp
+     (defun oni:with-diff-hl-p4-args (orig-fun &rest args)
+       (let ((p4-lowlevel-diff-switches '("-du0")))
+         (apply orig-fun args)))
+
+     (with-eval-after-load 'vc-p4
+       (add-function :around (symbol-function 'diff-hl-changes-buffer)
+                     #'oni:with-diff-hl-p4-args))
+   #+END_SRC
+
 ** Isearch
 
    Replace the Isearch mode line lighter with a magnifying glass icon.