diff -upr mlterm-3.9.1.org/uitoolkit/ui_screen.c mlterm-3.9.1.mod/uitoolkit/ui_screen.c
--- mlterm-3.9.1.org/uitoolkit/ui_screen.c	2021-02-14 19:19:05.164651000 +0900
+++ mlterm-3.9.1.mod/uitoolkit/ui_screen.c	2021-05-04 09:38:50.000000000 +0900
@@ -4071,7 +4071,7 @@ static void resize_window(ui_screen_t *s
 static void modify_line_space_and_offset(ui_screen_t *screen) {
   u_int font_height = ui_get_usascii_font(screen->font_man)->height;
 
-  if (screen->line_space < 0 && font_height < -screen->line_space * 4) {
+  if (screen->line_space < 0 && font_height < -screen->line_space) {
     bl_msg_printf("Ignore line_space (%d)\n", screen->line_space);
     screen->line_space = 0;
   }