diff --git a/sys/i386/isa/rtc.h b/sys/i386/isa/rtc.h
index 12d81b37ed5c..ba008b6517dd 100644
--- a/sys/i386/isa/rtc.h
+++ b/sys/i386/isa/rtc.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)rtc.h	7.1 (Berkeley) 5/12/91
- *	$Id: rtc.h,v 1.2 1993/10/16 13:46:16 rgrimes Exp $
+ *	$Id: rtc.h,v 1.3 1993/11/07 17:44:34 wollman Exp $
  */
 
 #ifndef _I386_ISA_RTC_H_
@@ -79,6 +79,7 @@
 #define	 RTCFDT_NONE	 0		/* none present */
 #define	 RTCFDT_360K	 0x10		/* 360K */
 #define	 RTCFDT_12M	 0x20		/* 1.2M */
+#define  RTCFDT_720K     0x30           /* 720K */
 #define	 RTCFDT_144M	 0x40		/* 1.44M */
 
 #define RTC_BASELO	0x15	/* low byte of basemem size */
diff --git a/sys/isa/rtc.h b/sys/isa/rtc.h
index 12d81b37ed5c..ba008b6517dd 100644
--- a/sys/isa/rtc.h
+++ b/sys/isa/rtc.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)rtc.h	7.1 (Berkeley) 5/12/91
- *	$Id: rtc.h,v 1.2 1993/10/16 13:46:16 rgrimes Exp $
+ *	$Id: rtc.h,v 1.3 1993/11/07 17:44:34 wollman Exp $
  */
 
 #ifndef _I386_ISA_RTC_H_
@@ -79,6 +79,7 @@
 #define	 RTCFDT_NONE	 0		/* none present */
 #define	 RTCFDT_360K	 0x10		/* 360K */
 #define	 RTCFDT_12M	 0x20		/* 1.2M */
+#define  RTCFDT_720K     0x30           /* 720K */
 #define	 RTCFDT_144M	 0x40		/* 1.44M */
 
 #define RTC_BASELO	0x15	/* low byte of basemem size */