diff --git a/src/lsp/defmacro.lsp b/src/lsp/defmacro.lsp
index 85bfa8a50..1b3d8bb7e 100644
--- a/src/lsp/defmacro.lsp
+++ b/src/lsp/defmacro.lsp
@@ -1,4 +1,4 @@
-;;;;  -*- Mode: Lisp; Syntax: Common-Lisp; Package: SYSTEM -*-
+;;;;  -*- Mode: Lisp; Syntax: Common-Lisp; Package: SYSTEM; indent-tabs-mode: nil -*-
 ;;;;
 ;;;;  Copyright (c) 1984, Taiichi Yuasa and Masami Hagiya.
 ;;;;  Copyright (c) 1990, Giuseppe Attardi.