Hello list, When I open a file with an unrecognized extension, my Emacs opens it in Fundamental mode (which is what I want). I have Evil enabled with (require 'evil) (evil-mode 1) but the file's buffer does not have undo-tree-mode enabled. I have to manually enable it with M-x undo-tree-mode . I tried adding (global-undo-tree-mode) in my ~/.emacs, but I get nothing. I also tried adding (add-hook 'evil-after-load-hook (lambda () (undo-tree-mode) ) ) but it doesn't help. If I set my emacs' default major mode to text-mode, then undo-tree gets enabled and everything works, but I don't want to use this workaround. I also tried deleting all of my ~/.emacs except for these lines (require 'evil) (evil-mode 1) , but I still get the same behavior. Interestingly, the *Messages* buffer has undo-tree-mode enabled with this same configuration. Does anyone have the same issues with Fundamental Mode + Undo Tree Mode when opening a file? -L