diff --git a/elixir-mode.el b/elixir-mode.el
index 629d7e97..cdcfc446 100644
--- a/elixir-mode.el
+++ b/elixir-mode.el
@@ -547,8 +547,8 @@ Argument END End of the region."
   (set (make-local-variable 'comment-start) "# ")
   (set (make-local-variable 'comment-end) "")
   (set (make-local-variable 'comment-use-syntax) t)
-  (set (make-variable-buffer-local 'tab-width) elixir-basic-offset)
-  (set (make-variable-buffer-local 'default-tab-width) elixir-basic-offset)
+  (set (make-local-variable 'tab-width) elixir-basic-offset)
+  (set (make-local-variable 'default-tab-width) elixir-basic-offset)
   (if (boundp 'syntax-propertize-function)
       (set (make-local-variable 'syntax-propertize-function) 'elixir-syntax-propertize))
   (smie-setup elixir-smie-grammar 'verbose-elixir-smie-rules ; 'elixir-smie-rules