diff --git a/sys/arch/vax/vax/subr.S b/sys/arch/vax/vax/subr.S
index e7df84e1c7a8..3538224e487c 100644
--- a/sys/arch/vax/vax/subr.S
+++ b/sys/arch/vax/vax/subr.S
@@ -1,4 +1,4 @@
-/*	$NetBSD: subr.S,v 1.25 2008/08/29 18:25:02 matt Exp $	   */
+/*	$NetBSD: subr.S,v 1.26 2009/04/10 13:40:38 tsutsui Exp $	   */
 
 /*
  * Copyright (c) 1994 Ludd, University of Lule}, Sweden.
@@ -440,7 +440,7 @@ JSBENTRY(Swtchto)
 #
 
 ENTRY(copyout, 0)
-	movl	8(%ap),%r2
+	movl	8(%ap),%r3
 	blss	3f		# kernel space
 	movl	4(%ap),%r1
 	brb	2f
@@ -448,13 +448,18 @@ ENTRY(copyout, 0)
 ENTRY(copyin, 0)
 	movl	4(%ap),%r1
 	blss	3f		# kernel space
-	movl	8(%ap),%r2
-2:	mfpr	$PR_ESP,%r3
-	movab	1f,(%r3)
-	movc3	12(%ap),(%r1),(%r2)
-1:	mfpr	$PR_ESP,%r3
-	clrl	(%r3)
+	movl	8(%ap),%r3
+2:	mfpr	$PR_ESP,%r2
+	movab	1f,(%r2)
+4:	tstw	14(%ap)		# check if >= 64K
+	bneq	5f
+	movc3	12(%ap),(%r1),(%r3)
+1:	mfpr	$PR_ESP,%r2
+	clrl	(%r2)
 	ret
+5:	movc3	$0xfffc,(%r1),(%r3)
+	subl2	$0xfffc,12(%ap)
+	brb	4b
 
 3:	mnegl	$1,%r0
 	ret