(mouse-scroll-subr): Handle if window-end returns nil.

1 files changed, 7 insertions, 5 deletions

diff --git a/lisp/mouse.el b/lisp/mouse.el
index 4741d5fc8f6..2241578cffc 100644
--- a/lisp/mouse.el
+++ b/lisp/mouse.el
@@ -478,11 +478,13 @@ Upon exit, point is at the far edge of the newly visible text."
                  (progn
                    (set-window-start window (point))
                    (if (natnump jump)
-                       (progn
-                         (goto-char (window-end window))
-                         ;; window-end doesn't reflect the window's new
-                         ;; start position until the next redisplay.  Hurrah.
-                         (vertical-motion (1- jump) window))
+                       (if (window-end window)
+                           (progn
+                             (goto-char (window-end window))
+                             ;; window-end doesn't reflect the window's new
+                             ;; start position until the next redisplay.
+                             (vertical-motion (1- jump) window))
+                         (vertical-motion (- (window-height window) 2)))
                      (goto-char (window-start window)))
                    (if overlay
                        (move-overlay overlay start (point)))