diff --git a/sys/dev/usb/usbcdc.h b/sys/dev/usb/usbcdc.h
index 34a0c94ca0e7..8b81dbb6ccbc 100644
--- a/sys/dev/usb/usbcdc.h
+++ b/sys/dev/usb/usbcdc.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: usbcdc.h,v 1.3 1999/01/03 01:09:18 augustss Exp $	*/
+/*	$NetBSD: usbcdc.h,v 1.6 2000/04/27 15:26:50 augustss Exp $	*/
 /*	$FreeBSD$	*/
 
 /*
@@ -146,4 +146,13 @@ typedef struct {
 } usb_cdc_notification_t;
 #define UCDC_NOTIFICATION_LENGTH 8
 
+/* Serial state bit masks */
+#define UCDC_MDM_RXCARRIER	0x01
+#define UCDC_MDM_TXCARRIER	0x02
+#define UCDC_MDM_BREAK		0x04
+#define UCDC_MDM_RING		0x08
+#define UCDC_MDM_FRAMING_ERR	0x10
+#define UCDC_MDM_PARITY_ERR	0x20
+#define UCDC_MDM_OVERRUN_ERR	0x40
+
 #endif /* _USBCDC_H_ */