diff --git a/lisp/org-clock.el b/lisp/org-clock.el
index b1041e2..467ffc4 100644
--- a/lisp/org-clock.el
+++ b/lisp/org-clock.el
@@ -244,6 +244,7 @@ to add an effort property.")
 (defvar org-clock-heading "")
 (defvar org-clock-heading-for-remember "")
 (defvar org-clock-start-time "")
+(defvar org-clock-used-in-this-session nil)
 
 (defvar org-clock-left-over-time nil
   "If non-nil, user cancelled a clock; this is when leftover time started.")
@@ -953,6 +954,7 @@ the clocking selection, associated with the letter `d'."
 	    (setq org-clock-idle-timer
 		  (run-with-timer 60 60 'org-resolve-clocks-if-idle))
 	    (message "Clock starts at %s - %s" ts msg-extra)
+            (setq org-clock-used-in-this-session t)
 	    (run-hooks 'org-clock-in-hook)))))))
 
 (defun org-clock-mark-default-task ()
@@ -1824,7 +1826,7 @@ This function is made for clock tables."
   "Persist various clock-related data to disk.
 The details of what will be saved are regulated by the variable
 `org-clock-persist'."
-  (when org-clock-persist
+  (when (and org-clock-persist org-clock-used-in-this-session)
     (let (b)
       (with-current-buffer (find-file (expand-file-name org-clock-persist-file))
 	(progn