diff --git a/tmux.h b/tmux.h
index 85719c07..58d0cdf0 100644
--- a/tmux.h
+++ b/tmux.h
@@ -403,6 +403,7 @@ enum tty_code_code {
 	TTYC_MS,
 	TTYC_OP,
 	TTYC_REV,
+	TTYC_RGB,
 	TTYC_RI,
 	TTYC_RMACS,
 	TTYC_RMCUP,
diff --git a/tty-term.c b/tty-term.c
index 9d026fa3..9f0cac56 100644
--- a/tty-term.c
+++ b/tty-term.c
@@ -240,6 +240,7 @@ static const struct tty_term_code_entry tty_term_codes[] = {
 	[TTYC_MS] = { TTYCODE_STRING, "Ms" },
 	[TTYC_OP] = { TTYCODE_STRING, "op" },
 	[TTYC_REV] = { TTYCODE_STRING, "rev" },
+	[TTYC_RGB] = { TTYCODE_FLAG, "RGB" },
 	[TTYC_RI] = { TTYCODE_STRING, "ri" },
 	[TTYC_RMACS] = { TTYCODE_STRING, "rmacs" },
 	[TTYC_RMCUP] = { TTYCODE_STRING, "rmcup" },
@@ -531,8 +532,11 @@ tty_term_find(char *name, int fd, char **cause)
 		code->type = TTYCODE_STRING;
 	}
 
-	/* On terminals with RGB colour (TC), fill in setrgbf and setrgbb. */
-	if (tty_term_flag(term, TTYC_TC) &&
+	/*
+	 * On terminals with RGB colour (Tc or RGB), fill in setrgbf and
+	 * setrgbb if they are missing.
+	 */
+	if ((tty_term_flag(term, TTYC_TC) || tty_term_flag(term, TTYC_RGB)) &&
 	    !tty_term_has(term, TTYC_SETRGBF) &&
 	    !tty_term_has(term, TTYC_SETRGBB)) {
 		code = &term->codes[TTYC_SETRGBF];
diff --git a/tty.c b/tty.c
index 01208a25..b293d41d 100644
--- a/tty.c
+++ b/tty.c
@@ -2051,11 +2051,15 @@ tty_try_colour(struct tty *tty, int colour, const char *type)
 
 	if (colour & COLOUR_FLAG_256) {
 		/*
-		 * If the user has specified -2 to the client, setaf and setab
-		 * may not work (or they may not want to use them), so send the
-		 * usual sequence.
+		 * If the user has specified -2 to the client (meaning
+		 * TERM_256COLOURS is set), setaf and setab may not work (or
+		 * they may not want to use them), so send the usual sequence.
+		 *
+		 * Also if RGB is set, setaf and setab do not support the 256
+		 * colour palette so use the sequences directly there too.
 		 */
-		if (tty->term_flags & TERM_256COLOURS)
+		if ((tty->term_flags & TERM_256COLOURS) ||
+		    tty_term_has(tty->term, TTYC_RGB))
 			goto fallback_256;
 
 		/*
@@ -2096,6 +2100,7 @@ tty_try_colour(struct tty *tty, int colour, const char *type)
 
 fallback_256:
 	xsnprintf(s, sizeof s, "\033[%s;5;%dm", type, colour & 0xff);
+	log_debug("%s: 256 colour fallback: %s", tty->client->name, s);
 	tty_puts(tty, s);
 	return (0);
 }