diff --git a/tools/gn/misc/emacs/gn-mode.el b/tools/gn/misc/emacs/gn-mode.el
index c7ee08b..14bcd93 100644
--- a/tools/gn/misc/emacs/gn-mode.el
+++ b/tools/gn/misc/emacs/gn-mode.el
@@ -132,6 +132,7 @@
   (setq-local comment-use-syntax t)
   (setq-local comment-start "#")
   (setq-local comment-end "")
+  (setq-local indent-tabs-mode nil)
 
   (setq-local fill-paragraph-function 'gn-fill-paragraph)