diff --git a/lisp/org-agenda.el b/lisp/org-agenda.el
index b3c7294a2..968b6bd50 100644
--- a/lisp/org-agenda.el
+++ b/lisp/org-agenda.el
@@ -6237,11 +6237,12 @@ defun org-agenda-show-clocking-issues
 	      (setq issue
 		    (format
 		     "No end time: (%s)"
-		     (org-duration-from-minutes
-		      (floor
-		       (- (float-time (org-current-time))
-			  (float-time (org-time-string-to-time (match-string 1))))
-		       60)))
+		     (let ((diff (floor
+		                  (- (float-time (org-current-time))
+			             (float-time (org-time-string-to-time (match-string 1))))
+		                  60)))
+                       (concat (if (> 0 diff) "-" "")
+                               (org-duration-from-minutes (abs diff)))))
 		    face (or (plist-get pl :no-end-time-face) face))
 	      (throw 'next t))
 	    (setq ts (match-string 1)