diff --git a/sys/amd64/isa/isa.h b/sys/amd64/isa/isa.h
index a7a8fef467c..4357f42e633 100644
--- a/sys/amd64/isa/isa.h
+++ b/sys/amd64/isa/isa.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)isa.h	5.7 (Berkeley) 5/9/91
- *	$Id: isa.h,v 1.12 1995/01/07 14:52:08 jkh Exp $
+ *	$Id: isa.h,v 1.13 1995/01/25 20:11:50 jmz Exp $
  */
 
 #ifndef _I386_ISA_ISA_H_
@@ -143,7 +143,7 @@
 #define	IO_TMRSIZE	16		/* 8253 programmable timers */
 #define	IO_NPXSIZE	16		/* 80387/80487 NPX registers */
 #define	IO_VGASIZE	16		/* VGA controllers */
-#define IO_EISASIZE	4096		/* EISA controllers */
+#define IO_EISASIZE	256		/* EISA controllers */
 #define	IO_PMPSIZE	2		/* 82347 power management peripheral */
 
 #endif	/* IO_ISASIZES */
diff --git a/sys/i386/isa/isa.h b/sys/i386/isa/isa.h
index a7a8fef467c..4357f42e633 100644
--- a/sys/i386/isa/isa.h
+++ b/sys/i386/isa/isa.h
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)isa.h	5.7 (Berkeley) 5/9/91
- *	$Id: isa.h,v 1.12 1995/01/07 14:52:08 jkh Exp $
+ *	$Id: isa.h,v 1.13 1995/01/25 20:11:50 jmz Exp $
  */
 
 #ifndef _I386_ISA_ISA_H_
@@ -143,7 +143,7 @@
 #define	IO_TMRSIZE	16		/* 8253 programmable timers */
 #define	IO_NPXSIZE	16		/* 80387/80487 NPX registers */
 #define	IO_VGASIZE	16		/* VGA controllers */
-#define IO_EISASIZE	4096		/* EISA controllers */
+#define IO_EISASIZE	256		/* EISA controllers */
 #define	IO_PMPSIZE	2		/* 82347 power management peripheral */
 
 #endif	/* IO_ISASIZES */