diff --git a/lisp/org-agenda.el b/lisp/org-agenda.el
index ca5ae40b9..d5abfffaf 100644
--- a/lisp/org-agenda.el
+++ b/lisp/org-agenda.el
@@ -9700,7 +9700,12 @@ Called with a universal prefix arg, show the priority instead of setting it."
 				  (line-end-position)
 				  '(display nil))
 	  (org-move-to-column
-	   (- (/ (window-width nil t) (window-font-width)) (length stamp)) t)
+           (- (if (fboundp 'window-font-width)
+                  (/ (window-width nil t) (window-font-width))
+                ;; Fall back to pre-9.3.3 behavior on Emacs <25.
+                (window-width))
+              (length stamp))
+           t)
           (add-text-properties
 	   (1- (point)) (point-at-eol)
 	   (list 'display (org-add-props stamp nil