diff --git a/tmux.h b/tmux.h
index fdea4145a..65bd00761 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1455 2026/10/09 13:12:14 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1456 2026/10/12 10:39:05 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -629,6 +629,7 @@ enum tty_code_code {
 	TTYC_KUP6,
 	TTYC_KUP7,
 	TTYC_MS,
+	TTYC_NCV,
 	TTYC_NOBR,
 	TTYC_OL,
 	TTYC_OP,
diff --git a/tty-term.c b/tty-term.c
index f2d8b67b6..e34a872b4 100644
--- a/tty-term.c
+++ b/tty-term.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-term.c,v 1.111 2026/09/22 14:10:26 nicm Exp $ */
+/* $OpenBSD: tty-term.c,v 1.112 2026/10/12 10:39:05 nicm Exp $ */
 
 /*
  * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -251,6 +251,7 @@ static const struct tty_term_code_entry tty_term_codes[] = {
 	[TTYC_KUP6] = { TTYCODE_STRING, "kUP6" },
 	[TTYC_KUP7] = { TTYCODE_STRING, "kUP7" },
 	[TTYC_MS] = { TTYCODE_STRING, "Ms" },
+	[TTYC_NCV] = { TTYCODE_NUMBER, "ncv" },
 	[TTYC_NOBR] = { TTYCODE_STRING, "Nobr" },
 	[TTYC_OL] = { TTYCODE_STRING, "ol" },
 	[TTYC_OP] = { TTYCODE_STRING, "op" },
diff --git a/tty.c b/tty.c
index 161747655..ad2853d42 100644
--- a/tty.c
+++ b/tty.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty.c,v 1.485 2026/10/07 07:34:59 nicm Exp $ */
+/* $OpenBSD: tty.c,v 1.486 2026/10/12 10:39:05 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -51,6 +51,7 @@ static void	tty_check_bg(struct tty *, struct colour_palette *,
 		    struct grid_cell *);
 static void	tty_check_us(struct tty *, struct colour_palette *,
 		    struct grid_cell *);
+static void	tty_check_ncv(struct tty *, struct grid_cell *);
 static int	tty_map_theme_colour(struct tty *, int);
 static void	tty_colours_fg(struct tty *, const struct grid_cell *);
 static void	tty_colours_bg(struct tty *, const struct grid_cell *);
@@ -2350,6 +2351,33 @@ tty_dim_default_colour(struct tty *tty, int c, int foreground)
 	return (c);
 }
 
+static void
+tty_check_ncv(struct tty *tty, struct grid_cell *gc)
+{
+	int	n;
+
+	if (COLOUR_DEFAULT(gc->fg) && COLOUR_DEFAULT(gc->bg))
+		return;
+
+	n = tty_term_number(tty->term, TTYC_NCV);
+	if (n & 2)
+		gc->attr &= ~GRID_ATTR_ALL_UNDERSCORE;
+	if (n & 4)
+		gc->attr &= ~GRID_ATTR_REVERSE;
+	if (n & 8)
+		gc->attr &= ~GRID_ATTR_BLINK;
+	if (n & 16)
+		gc->attr &= ~GRID_ATTR_DIM;
+	if (n & 32)
+		gc->attr &= ~GRID_ATTR_BRIGHT;
+	if (n & 64)
+		gc->attr &= ~GRID_ATTR_HIDDEN;
+	if (n & 256)
+		gc->attr &= ~GRID_ATTR_CHARSET;
+	if (n & 32768)
+		gc->attr &= ~GRID_ATTR_ITALICS;
+}
+
 void
 tty_attributes(struct tty *tty, const struct grid_cell *gc,
     const struct tty_style_ctx *style_ctx)
@@ -2420,6 +2448,7 @@ tty_attributes(struct tty *tty, const struct grid_cell *gc,
 	tty_check_fg(tty, palette, &gc2);
 	tty_check_bg(tty, palette, &gc2);
 	tty_check_us(tty, palette, &gc2);
+	tty_check_ncv(tty, &gc2);
 
 	/*
 	 * If any bits are being cleared or the underline colour is now default,