diff --git a/src/xdisp.c b/src/xdisp.c
index 0b88b434bc2..a583e102528 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -18891,8 +18891,6 @@ set_vertical_scroll_bar (struct window *w)
 	{
 	  whole = BUF_ZV (buf) - BUF_BEGV (buf);
 	  start = marker_position (w->start) - BUF_BEGV (buf);
-	  /* I don't think this is guaranteed to be right.  For the
-	     moment, we'll pretend it is.  */
 	  end = BUF_Z (buf) - window_end_pos - BUF_BEGV (buf);
 	}
       else