diff --git a/src/emacs/lean-mode.el b/src/emacs/lean-mode.el
index e78c60c0c..ca584cf5c 100644
--- a/src/emacs/lean-mode.el
+++ b/src/emacs/lean-mode.el
@@ -4,6 +4,7 @@
 ;; Author: Leonardo de Moura
 ;;         Soonho Kong
 ;;
+(require 'cl-lib)
 (require 'generic-x)
 (require 'compile)
 (require 'flymake)
@@ -82,7 +83,7 @@
       (abbrev-mode 1)
       (when (and lean-rule-column
                  lean-show-rule-column-method)
-        (case lean-show-rule-column-method
+        (cl-case lean-show-rule-column-method
           ('vline (setq fci-rule-column lean-rule-column)
                   (add-hook 'lean-mode-hook 'fci-mode))))
       (if lean-delete-trailing-whitespace
diff --git a/src/emacs/lean-settings.el b/src/emacs/lean-settings.el
index 3b26f32ba..773c5bad2 100644
--- a/src/emacs/lean-settings.el
+++ b/src/emacs/lean-settings.el
@@ -4,10 +4,12 @@
 ;; Author: Soonho Kong
 ;;
 
+(require 'cl-lib)
+
 (defgroup lean nil "Lean mode" :prefix 'lean :group 'languages)
 
 (defvar lean-default-executable-name
-  (case system-type
+  (cl-case system-type
     ('gnu          "lean")
     ('gnu/linux    "lean")
     ('gnu/kfreebsd "lean")
@@ -16,20 +18,17 @@
     ('windows-nt   "lean.exe")
     ('cygwin       "lean.exe") ;; TODO(soonhok): check this
     )
-  "Default executable name of Lean"
-  )
+  "Default executable name of Lean")
 
 (defcustom lean-rootdir nil
   "Full pathname of lean root directory. It should be defined by user."
   :group 'lean
-  :type 'string
-  )
+  :type 'string)
 
 (defcustom lean-executable-name lean-default-executable-name
   "Name of lean executable"
   :group 'lean
-  :type 'string
-  )
+  :type 'string)
 
 (defcustom lean-delete-trailing-whitespace nil
   "Set this variable to true to automatically delete trailing