diff --git a/tests/sys/kern/coredump_phnum_helper.c b/tests/sys/kern/coredump_phnum_helper.c
index da023e691a24..0dff59b918d9 100644
--- a/tests/sys/kern/coredump_phnum_helper.c
+++ b/tests/sys/kern/coredump_phnum_helper.c
@@ -1,61 +1,64 @@
 /*
  * Copyright (c) 2016, Conrad Meyer
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * 1. Redistributions of source code must retain the above copyright notice,
  * this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright notice,
  * this list of conditions and the following disclaimer in the documentation
  * and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  *
  * $FreeBSD$
  */
 
 #include <sys/param.h>
 #include <sys/mman.h>
 
 #include <err.h>
 #include <stdint.h>
 #include <stdlib.h>
 
 /*
  * This program is intended to create a bunch of segment mappings, then dump
  * core.
  */
 int
 main(int argc __unused, char **argv __unused)
 {
 	void *v;
-	unsigned i;
+	size_t i, pages;
 
-	for (i = 0; i < UINT16_MAX + 1000; i++) {
+	pages = UINT16_MAX + 1000;
+	v = mmap(NULL, pages * PAGE_SIZE, PROT_READ | PROT_WRITE,
+	    MAP_ANON | MAP_PRIVATE, -1, 0);
+	if (v == NULL)
+		err(1, "mmap");
+	for (i = 0; i < pages; i += 2) {
 		/*
-		 * Alternate protections; otherwise the kernel will just extend
-		 * the adjacent same-protection previous mapping.
+		 * Alternate protections to interleave RW and R PT_LOAD
+		 * segments.
 		 */
-		v = mmap(NULL, PAGE_SIZE,
-		    (((i % 2) == 0) ? PROT_READ : 0) | PROT_WRITE,
-		    MAP_ANON | MAP_PRIVATE, -1, 0);
-		if (v == MAP_FAILED)
-			err(1, "mmap");
+		if (mprotect((char *)v + i * PAGE_SIZE, PAGE_SIZE,
+		    PROT_READ) != 0)
+			err(1, "mprotect");
 	}
 
 	/* Dump core. */
 	abort();
 }