diff --git a/init.el b/init.el
index c12bb25..182a2b8 100644
--- a/init.el
+++ b/init.el
@@ -187,13 +187,19 @@
 (require 'mozc nil t)
 (setq default-input-method "japanese-mozc")
 
+;; undo-tree
+(use-package undo-tree
+  :defer nil
+  :config
+  (global-undo-tree-mode))
+
 ;; evil
 (use-package evil
   :init
   (setq evil-want-integration t
         evil-want-C-d-scroll nil
         evil-want-keybinding nil
-        evil-undo-system 'undo-redo
+        evil-undo-system 'undo-tree
         evil-search-module 'isearch
         evil-respect-visual-line-mode t)
   :config
@@ -944,15 +950,16 @@ argument."
 (use-package fricas
   :ensure nil
   :custom
-  (fricas-run-command "fricas -nox")
+  (fricas-run-command "fricas -nosman")
   :init
   ;; Fix `fricas-mode' messing up `completion-at-point-functions'
   (advice-add #'fricas-mode :around
               #'(lambda (oldfun &rest r)
+                  (let ((temp-capfs))
                     (let ((completion-at-point-functions '(t)))
                       (apply oldfun r)
-                      (setq-local completion-at-point-functions
-                                  completion-at-point-functions)))
+                      (setq temp-capfs completion-at-point-functions))
+                    (setq-local completion-at-point-functions temp-capfs)))
               '((name . "my/-fricas-fix-capfs")))
   :config
   (face-spec-set 'fricas-type-time '((t (:foreground unspecified
@@ -968,8 +975,8 @@ argument."
                                        :background unspecified
                                        :weight bold
                                        :inherit fricas-prompt))))
-  (face-spec-set 'fricas-TeX '((t (:foreground unspecified
-                                   :background unspecified
+  (face-spec-set 'fricas-TeX '((t (:foreground "black"
+                                   :background "white"
                                    :inherit fricas-prompt)))))
 
 ;; gnuplot (mostly for org-plot)