diff --git a/runtime/ftplugin/just.vim b/runtime/ftplugin/just.vim
index 6f2acddf96..7cf188a774 100644
--- a/runtime/ftplugin/just.vim
+++ b/runtime/ftplugin/just.vim
@@ -2,6 +2,7 @@
 " Language:	Justfile
 " Maintainer:	Peter Benjamin <@pbnj>
 " Last Change:	2025 Jan 19
+" 2026 May 17 by Vim Project: add 'suffixesadd' #20197
 " Credits:	The original author, Noah Bogart <https://github.com/NoahTheDuke/vim-just/>
 
 " Only do this when not done yet for this buffer
@@ -13,5 +14,6 @@ let b:did_ftplugin = 1
 setlocal iskeyword+=-
 setlocal comments=n:#
 setlocal commentstring=#\ %s
+setlocal suffixesadd=.just
 
-let b:undo_ftplugin = "setlocal iskeyword< comments< commentstring<"
+let b:undo_ftplugin = "setlocal iskeyword< comments< commentstring< suffixesadd<"