diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index 93eb3c496ff1e8..2d98e65d2a783b 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -128,6 +128,8 @@ struct serial_rs485 {
 							   (if supported) */
 	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
 	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
+	__u32	delay_rts_before_send_ns;	/* Delay (nanoseconds) */
+	__u32	delay_rts_after_send_ns;	/* Delay (nanoseconds) */
 	__u32	padding[5];		/* Memory is cheap, new structs
 					   are a royal PITA .. */
 };