 CLOCK: [2018-01-11 Thu 13:33]
 CLOCK: [2018-01-07 Sun 13:00]--[2018-01-11 Thu 13:33] => 96:33
 :END:
-"))))))
+")))))))
 
 (ert-deftest timeline-tools-test-add-clockline-to-marker-3 ()
   "Test `timeline-tools-add-clockline-to-marker’ with running
 clock at same task."
-  (with-temp-buffer
-    (insert "
+  (let ((system-time-locale "C"))
+    (with-temp-buffer
+      (insert "
 * Task 1
 :LOGBOOK:
 CLOCK: [2018-01-08 Mon 16:15]--[2018-01-10 Wed 13:10] => 44:55

CLOCK: [2018-01-07 Sun 15:13]--[2018-01-07 Sun 16:17] =>  1:04
:END:
")
    (org-mode)
    (let (;; simulate running clock at Task 2
          (org-clock-hd-marker (progn (goto-char 216) (point-marker)))
          (org-clock-marker (progn (goto-char 264) (point-marker)))
          (org-clock-start-time (org-time-string-to-time "[2018-01-10 Wed 13:10]")))
      (let ((result (timeline-tools-add-clockline-to-marker
                     (progn (goto-char 2) (point-marker))
                     (org-time-string-to-seconds "[2018-01-07 Sun 13:00]")
                     (org-time-string-to-seconds "[2018-01-11 Thu 13:33]"))))

        (should (null result))
        (should (equal org-clock-start-time
                       (append (org-time-string-to-time "[2018-01-11 Thu 13:33]")
                               '(0 0))))
        (should (equal (buffer-string)
                       "
* Task 1
:LOGBOOK:
CLOCK: [2018-01-07 Sun 13:00]--[2018-01-11 Thu 13:33] => 96:33

:LOGBOOK:
CLOCK: [2018-01-07 Sun 13:00]--[2018-01-11 Thu 13:33] => 96:33
:END:
"))))))

(ert-deftest timeline-tools-test-add-clockline-to-marker-2 ()
  "Test `timeline-tools-add-clockline-to-marker’ with running
clock at same task."
  (let ((system-time-locale "C"))
    (with-temp-buffer
      (insert "
* Task 1
:LOGBOOK:
CLOCK: [2018-01-10 Wed 10:07]--[2018-01-12 Fri 14:00] => 51:53
