diff --git a/tmux.h b/tmux.h
index 048d6c43f..de254a9f4 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tmux.h,v 1.1445 2026/09/22 06:46:50 nicm Exp $ */
+/* $OpenBSD: tmux.h,v 1.1447 2026/09/22 14:10:26 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -1738,6 +1738,7 @@ struct tty_term {
 #define TERM_VT100LIKE 0x20
 #define TERM_SIXEL 0x40
 #define TERM_INVALIDMS 0x80
+#define TERM_NOREPLACE 0x100
 	int		 flags;
 
 	LIST_ENTRY(tty_term) entry;
@@ -3007,7 +3008,7 @@ void	tty_default_colours(struct grid_cell *, struct window_pane *, u_int *);
 /* tty-term.c */
 extern struct tty_terms tty_terms;
 u_int		 tty_term_ncodes(void);
-void		 tty_term_apply(struct tty_term *, const char *, int);
+void		 tty_term_apply(struct tty_term *, const char *, int, int);
 void		 tty_term_apply_overrides(struct tty_term *);
 struct tty_term *tty_term_create(struct tty *, char *, char **, u_int, char **);
 void		 tty_term_free(struct tty_term *);
diff --git a/tty-features.c b/tty-features.c
index 0b12745e2..284943caf 100644
--- a/tty-features.c
+++ b/tty-features.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-features.c,v 1.43 2026/08/31 12:41:03 kirill Exp $ */
+/* $OpenBSD: tty-features.c,v 1.45 2026/09/22 14:10:26 nicm Exp $ */
 
 /*
  * Copyright (c) 2020 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -198,7 +198,7 @@ static const char *const tty_feature_cstyle_capabilities[] = {
 static const struct tty_feature tty_feature_cstyle = {
 	"cstyle",
 	tty_feature_cstyle_capabilities,
-	0
+	TERM_NOREPLACE
 };
 
 /* Terminal supports cursor colours. */
@@ -541,11 +541,11 @@ tty_apply_features(struct tty_term *term)
 			capability = tf->capabilities;
 			while (*capability != NULL) {
 				log_debug("adding capability: %s", *capability);
-				tty_term_apply(term, *capability, 1);
+				tty_term_apply(term, *capability, 1, tf->flags);
 				capability++;
 			}
 		}
-		term->flags |= tf->flags;
+		term->flags |= (tf->flags & ~TERM_NOREPLACE);
 		if (tf == &tty_feature_utf8)
 			c->flags |= CLIENT_UTF8;
 	}
diff --git a/tty-term.c b/tty-term.c
index 6b149fcee..35df5c778 100644
--- a/tty-term.c
+++ b/tty-term.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tty-term.c,v 1.109 2026/08/25 08:37:08 nicm Exp $ */
+/* $OpenBSD: tty-term.c,v 1.111 2026/09/22 14:10:26 nicm Exp $ */
 
 /*
  * Copyright (c) 2008 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -362,7 +362,8 @@ tty_term_override_next(const char *s, size_t *offset)
 }
 
 void
-tty_term_apply(struct tty_term *term, const char *capabilities, int quiet)
+tty_term_apply(struct tty_term *term, const char *capabilities, int quiet,
+    int flags)
 {
 	const struct tty_term_code_entry	*ent;
 	struct tty_code				*code;
@@ -405,6 +406,9 @@ tty_term_apply(struct tty_term *term, const char *capabilities, int quiet)
 			if (strcmp(s, ent->name) != 0)
 				continue;
 			code = &term->codes[i];
+			if ((flags & TERM_NOREPLACE) &&
+			    code->type != TTYCODE_NONE)
+				continue;
 
 			if (remove) {
 				code->type = TTYCODE_NONE;
@@ -457,7 +461,7 @@ tty_term_apply_overrides(struct tty_term *term)
 		offset = 0;
 		first = tty_term_override_next(s, &offset);
 		if (first != NULL && fnmatch(first, term->name, 0) == 0)
-			tty_term_apply(term, s + offset, 0);
+			tty_term_apply(term, s + offset, 0, 0);
 		a = options_array_next(a);
 	}