diff --git a/drivers/tty/serial/rsci.c b/drivers/tty/serial/rsci.c
index 15ed6cf5c6c5..5a58c783fe8c 100644
--- a/drivers/tty/serial/rsci.c
+++ b/drivers/tty/serial/rsci.c
@@ -35,12 +35,6 @@ MODULE_IMPORT_NS("SH_SCI");
 #define RDR_FPER		BIT(11) /* FIFO Parity Error */
 #define RDR_RDAT_MSK		GENMASK(8, 0)
 
-/* TDR (Transmit Data Register) */
-#define TDR_MPBT		BIT(9)	/* Multiprocessor Transfer */
-#define TDR_TDAT_9BIT_LSHIFT	0
-#define TDR_TDAT_9BIT_VAL	0x1FF
-#define TDR_TDAT_9BIT_MSK	(TDR_TDAT_9BIT_VAL << TDR_TDAT_9BIT_LSHIFT)
-
 /* CCR0 (Common Control Register 0) */
 #define CCR0_SSE		BIT(24)	/* SSn# Pin Function Enable */
 #define CCR0_TEIE		BIT(21)	/* Transmit End Interrupt Enable */