diff --git a/init.el b/init.el
index c082ee1..0688082 100644
--- a/init.el
+++ b/init.el
@@ -290,6 +290,7 @@
                (list "^:Proj:python/" ":Proj:Py:")
                t)
   (sml/setup)
+  (require 'cl-lib)
   (setq-default header-line-format
                 '(""
                   mode-line-mule-info
@@ -312,7 +313,7 @@
   ;; Add sml/pre-id-separator after mode-line-front-space
   (let* ((front-space-position (1+ (cl-position 'mode-line-front-space mode-line-format)))
          (mode-line-rest (nthcdr front-space-position mode-line-format))
-         (mode-line-beg (subseq mode-line-format 0 front-space-position)))
+         (mode-line-beg (cl-subseq mode-line-format 0 front-space-position)))
     (setq-default mode-line-format (nconc mode-line-beg
                                           (list sml/pre-id-separator)
                                           mode-line-rest))))