diff --git a/runtime/ftplugin/mma.vim b/runtime/ftplugin/mma.vim
new file mode 100644
index 0000000..ce4cee1
--- /dev/null
+++ b/runtime/ftplugin/mma.vim
@@ -0,0 +1,16 @@
+" Vim filetype plugin file
+" Language:	Mathematica
+" Maintainer:	Ian Ford <ianf@wolfram.com>
+" Last Change:	22 January 2019
+
+" Only do this when not done yet for this buffer
+if exists("b:did_ftplugin")
+	finish
+endif
+
+" Don't load another plugin for this buffer
+let b:did_ftplugin = 1
+
+let b:undo_ftplugin = "setlocal commentstring<"
+
+setlocal commentstring=\(*%s*\)