diff --git a/src/winio.c b/src/winio.c
index 73eaa9b7f5c07a4f3eb32cb08f624a750c6d06d3..ff37fc1182c3614702b4112e590ead00a21f54ac 100644
--- a/src/winio.c
+++ b/src/winio.c
@@ -3505,9 +3505,11 @@ int need_vertical_update(size_t old_pww)
  * scrolling.  direction is the direction to scroll, either UP or DOWN,
  * and nlines is the number of lines to scroll.
  *
- * Note that we don't draw the topmost or bottommost lines before or
- * after scrolling, since we can make no assumptions about which of the
- * two is the current line at either time. */
+ * We assume that the topmost and bottommost lines of the scrolled
+ * region are where the current line was before and will be after
+ * scrolling, and hence don't draw them, since we can't know which is
+ * which.  edit_redraw() should be used to draw these lines, and to
+ * redraw marked lines, if applicable. */
 void edit_scroll(updown direction, int nlines)
 {
     const filestruct *foo;