diff --git a/sys/arch/hp300/hp300/machdep.c b/sys/arch/hp300/hp300/machdep.c
index 1af6497e2565..2e9140dde324 100644
--- a/sys/arch/hp300/hp300/machdep.c
+++ b/sys/arch/hp300/hp300/machdep.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: machdep.c,v 1.73 1996/10/18 08:57:14 thorpej Exp $	*/
+/*	$NetBSD: machdep.c,v 1.74 1996/10/19 08:51:33 thorpej Exp $	*/
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -201,6 +201,7 @@ consinit()
 void
 cpu_startup()
 {
+	extern char *etext;
 	register unsigned i;
 	register caddr_t v, firstaddr;
 	int base, residual;
@@ -416,11 +417,16 @@ again:
 		nbuf, bufpages * CLBYTES);
 
 	/*
-	 * Tell the VM system that page 0 isn't mapped.
+	 * Tell the VM system that page 0 isn't mapped and that
+	 * writing to kernel text isn't allowed.  If we don't
+	 * do the latter, we might end up COW'ing the text segment!
 	 */
 	if (vm_map_protect(kernel_map, 0, NBPG, VM_PROT_NONE, TRUE)
 	    != KERN_SUCCESS)
 		panic("can't mark page 0 off-limits");
+	if (vm_map_protect(kernel_map, NBPG, hp300_round_page(&etext),
+	    VM_PROT_READ|VM_PROT_EXECUTE, TRUE) != KERN_SUCCESS)
+		panic("can't protect kernel text");
 
 	/*
 	 * Set up CPU-specific registers, cache, etc.