diff --git a/sys/pc98/pc98/pc98.c b/sys/pc98/pc98/pc98.c
index a3c9bc36c214..b7d96a10e299 100644
--- a/sys/pc98/pc98/pc98.c
+++ b/sys/pc98/pc98/pc98.c
@@ -34,7 +34,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)isa.c	7.2 (Berkeley) 5/13/91
- *	$Id: pc98.c,v 1.54 1998/10/22 05:58:45 bde Exp $
+ *	$Id: pc98.c,v 1.55 1998/12/02 08:04:12 kato Exp $
  */
 
 /*
@@ -426,10 +426,6 @@ isa_configure()
 		if (!dvp->id_driver->sensitive_hw)
 			config_isadev(dvp, (u_int *)NULL);
 
-	bio_imask |= SWI_CLOCK_MASK;
-	net_imask |= SWI_NET_MASK;
-	tty_imask |= SWI_TTY_MASK;
-
 /*
  * XXX we should really add the tty device to net_imask when the line is
  * switched to SLIPDISC, and then remove it when it is switched away from
@@ -447,8 +443,6 @@ isa_configure()
 	tty_imask = net_imask;
 #endif
 
-	/* bio_imask |= tty_imask ;  can some tty devices use buffers? */
-
 	if (bootverbose)
 		printf("imasks: bio %x, tty %x, net %x\n",
 		       bio_imask, tty_imask, net_imask);