diff --git a/lisp/org-table.el b/lisp/org-table.el
index 7b91f3670..c5a3aca39 100644
--- a/lisp/org-table.el
+++ b/lisp/org-table.el
@@ -2099,7 +2099,7 @@ If NLAST is a number, only the NLAST fields will actually be summed."
 			   h (floor (/ diff 3600)) diff (mod diff 3600)
 			   m (floor (/ diff 60)) diff (mod diff 60)
 			   s diff)
-		     (format "%d:%02d:%02d" h m s))))
+		     (format "%.0f:%02.0f:%02.0f" h m s))))
 	(kill-new sres)
 	(if (org-called-interactively-p 'interactive)
 	    (message "%s"