diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 23a7ab0de444..acbb47c640bf 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3464,10 +3464,10 @@ EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
 
 /* Compile-time assertions for serial_rs485 layout */
 static_assert(offsetof(struct serial_rs485, padding) ==
-              (offsetof(struct serial_rs485, delay_rts_after_send) + sizeof(__u32)));
+	      (offsetof(struct serial_rs485, delay_rts_after_send_ns) + sizeof(__u32)));
 static_assert(offsetof(struct serial_rs485, padding1) ==
 	      offsetof(struct serial_rs485, padding[1]));
-static_assert((offsetof(struct serial_rs485, padding[4]) + sizeof(__u32)) ==
+static_assert((offsetof(struct serial_rs485, padding[2]) + sizeof(__u32)) ==
 	      sizeof(struct serial_rs485));
 
 MODULE_DESCRIPTION("Serial driver core");
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
index cea06924b295..faa8828efd6a 100644
--- a/include/uapi/linux/serial.h
+++ b/include/uapi/linux/serial.h
@@ -134,16 +134,18 @@ struct serial_rs485 {
 
 	__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 before send (nanoseconds) */
+	__u32	delay_rts_after_send_ns;	/* Delay after send (nanoseconds) */
 
 	/* The fields below are defined by flags */
 	union {
-		__u32	padding[5];		/* Memory is cheap, new structs are a pain */
+		__u32	padding[3];		/* Memory is cheap, new structs are a pain */
 
 		struct {
 			__u8	addr_recv;
 			__u8	addr_dest;
 			__u8	padding0[2];
-			__u32	padding1[4];
+			__u32	padding1[2];
 		};
 	};
 };