1 files changed, 6 insertions, 0 deletions

diff --git a/src/w32term.c b/src/w32term.c
index eb45d30b54b..5f5a3f954a9 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -2909,6 +2909,12 @@ x_draw_glyph_string (s)
                   position = (s->font->descent + 1) / 2;
                 }
             }
+          /* Check the sanity of thickness and position.  We should
+             avoid drawing underline out of the current line area.  */
+          if (s->y + s->height <= s->ybase + position)
+            position = s->y + s->height - 1;
+          if (s->y + s->height < s->ybase + position + thickness)
+            thickness = (s->y + s->height) - (s->ybase + position);
           s->underline_thickness = thickness;
           s->underline_position =position;
           y = s->ybase + position;