2 files changed, 6 insertions, 4 deletions

diff --git a/src/window.c b/src/window.c
index 374ef0f838f..753ebc16fbf 100644
--- a/src/window.c
+++ b/src/window.c
@@ -4813,8 +4813,9 @@ window_scroll_pixel_based (Lisp_Object window, int n, bool whole, bool noerror)
   SET_TEXT_POS_FROM_MARKER (start, w->start);
   /* Scrolling a minibuffer window via scroll bar when the echo area
      shows long text sometimes resets the minibuffer contents behind
-     our backs.  */
-  if (CHARPOS (start) > ZV)
+     our backs.  Also, someone might narrow-to-region and immediately
+     call a scroll function.  */
+  if (CHARPOS (start) > ZV || CHARPOS (start) < BEGV)
     SET_TEXT_POS (start, BEGV, BEGV_BYTE);
 
   /* If PT is not visible in WINDOW, move back one half of
diff --git a/src/xdisp.c b/src/xdisp.c
index dc68cd48e5f..d1e884820b6 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1317,8 +1317,9 @@ pos_visible_p (struct window *w, ptrdiff_t charpos, int *x, int *y,
   SET_TEXT_POS_FROM_MARKER (top, w->start);
   /* Scrolling a minibuffer window via scroll bar when the echo area
      shows long text sometimes resets the minibuffer contents behind
-     our backs.  */
-  if (CHARPOS (top) > ZV)
+     our backs.  Also, someone might narrow-to-region and immediately
+     call a scroll function.  */
+  if (CHARPOS (top) > ZV || CHARPOS (top) < BEGV)
     SET_TEXT_POS (top, BEGV, BEGV_BYTE);
 
   /* If the top of the window is after CHARPOS, the latter is surely