diff --git a/runtime/ftplugin/diff.vim b/runtime/ftplugin/diff.vim
index 3fe1b84..0464290 100644
--- a/runtime/ftplugin/diff.vim
+++ b/runtime/ftplugin/diff.vim
@@ -1,7 +1,7 @@
 " Vim filetype plugin file
 " Language:	Diff
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
-" Last Change:	2005 Jul 27
+" Last Change:	2020 Jul 18
 
 " Only do this when not done yet for this buffer
 if exists("b:did_ftplugin")
@@ -13,3 +13,6 @@
 
 " Don't use modelines in a diff, they apply to the diffed file
 setlocal nomodeline
+
+" If there are comments they start with #
+let &commentstring = "# %s"