diff --git a/src/xdisp.c b/src/xdisp.c
index 840699d00fb..fed58799eaa 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -16920,7 +16920,7 @@ redisplay_window (Lisp_Object window, bool just_this_one_p)
       if (scroll_conservatively > SCROLL_LIMIT)
 	{
 	  int window_total_lines
-	    = WINDOW_TOTAL_LINES (w) * FRAME_LINE_HEIGHT (f) * frame_line_height;
+	    = WINDOW_TOTAL_LINES (w) * FRAME_LINE_HEIGHT (f) / frame_line_height;
 	  int margin =
 	    scroll_margin > 0
 	    ? min (scroll_margin, window_total_lines / 4)