Apply by doing:
        cd /usr/src
        patch -p0 < 006_locore.patch

And then rebuild your kernel.

Index: sys/arch/alpha/alpha/locore.s
===================================================================
RCS file: /cvs/src/sys/arch/alpha/alpha/locore.s,v
retrieving revision 1.10
retrieving revision 1.11
diff -u -r1.10 -r1.11
--- sys/arch/alpha/alpha/locore.s	1999/09/26 11:07:32	1.10
+++ sys/arch/alpha/alpha/locore.s	1999/11/13 21:33:44	1.11
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.s,v 1.10 1999/09/26 11:07:32 kstailey Exp $	*/
+/*	$OpenBSD: locore.s,v 1.11 1999/11/13 21:33:44 deraadt Exp $	*/
 /*	$NetBSD: locore.s,v 1.27 1996/12/03 19:54:16 cgd Exp $	*/
 
 /*
@@ -858,7 +858,9 @@
 	LDGP(pv)
 
 	mov	a2, t0			/* t0 = i = len */
-	beq	a2, Lcopystr2		/* if (len == 0), bail out */
+	bne	a2, Lcopystr1		/* if (len != 0), proceed */
+	ldiq	t1, 1			/* else bail */
+	br	zero, Lcopystr2
 
 Lcopystr1:
 	ldq_u	t1, 0(a0)		/* t1 = *from */
@@ -882,7 +884,7 @@
 Lcopystr3:
 	beq	t1, Lcopystr4		/* *from == '\0'; leave quietly */
 
-	ldiq	v0, ENAMETOOLONG		/* *from != '\0'; error. */
+	ldiq	v0, ENAMETOOLONG	/* *from != '\0'; error. */
 	RET
 
 Lcopystr4: