diff --git a/elisp/extras.el b/elisp/extras.el
index 4fbbe30..0ae2b24 100644
--- a/elisp/extras.el
+++ b/elisp/extras.el
@@ -95,6 +95,9 @@
 
 ;; language server
 (use-package lsp-mode)
+(use-package lsp-treemacs)
+(use-package yasnippet)
+(use-package dap-mode)
 
 ;; R
 (use-package ess
diff --git a/elisp/settings.el b/elisp/settings.el
index 6d909d8..c3e5a7c 100644
--- a/elisp/settings.el
+++ b/elisp/settings.el
@@ -28,6 +28,9 @@
 	  (lambda ()
 	    (c-set-style "linux")))
 
+;; Always use spaces, never tabs
+(setq-default indent-tabs-mode nil)
+
 ;; remove trailing white spaces before saving
 (add-hook 'before-save-hook 'delete-trailing-whitespace)