diff --git a/include/ssp/ssp.h b/include/ssp/ssp.h
--- a/include/ssp/ssp.h
+++ b/include/ssp/ssp.h
@@ -83,6 +83,13 @@
 #define __ssp_redirect0(rtype, fun, args, call) \
     __ssp_redirect_raw(rtype, fun, fun, args, call, 1, __ssp_bos0)
 
+/*
+ * Take caution when using __ssp_overlap!  Don't use it in contexts where we
+ * can end up with double-evaluation of a statement with some side-effects.
+ */
+#define __ssp_overlap(a, b, l) \
+    (((a) <= (b) && (b) < (a) + (l)) || ((b) <= (a) && (a) < (b) + (l)))
+
 __BEGIN_DECLS
 void __stack_chk_fail(void) __dead2;
 void __chk_fail(void) __dead2;
diff --git a/lib/libc/secure/memcpy_chk.c b/lib/libc/secure/memcpy_chk.c
--- a/lib/libc/secure/memcpy_chk.c
+++ b/lib/libc/secure/memcpy_chk.c
@@ -37,8 +37,6 @@
 #include <ssp/string.h>
 #undef memcpy
 
-#include "ssp_internal.h"
-
 void *
 __memcpy_chk(void * __restrict dst, const void * __restrict src, size_t len,
     size_t slen)
diff --git a/lib/libc/secure/ssp_internal.h b/lib/libc/secure/ssp_internal.h
deleted file mode 100644
--- a/lib/libc/secure/ssp_internal.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/*	$NetBSD: ssp.h,v 1.13 2015/09/03 20:43:47 plunky Exp $	*/
-
-/*-
- * Copyright (c) 2006, 2011 The NetBSD Foundation, Inc.
- * All rights reserved.
- *
- * This code is derived from software contributed to The NetBSD Foundation
- * by Christos Zoulas.
- *
- * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
- */
-#ifndef _SECURE_SSP_INTERNAL_H_
-#define _SECURE_SSP_INTERNAL_H_
-
-#define __ssp_overlap(a, b, l) \
-    (((a) <= (b) && (b) < (a) + (l)) || ((b) <= (a) && (a) < (b) + (l)))
-
-#endif /* _SECURE_SSP_INTERNAL_H_ */
diff --git a/lib/libc/secure/stpcpy_chk.c b/lib/libc/secure/stpcpy_chk.c
--- a/lib/libc/secure/stpcpy_chk.c
+++ b/lib/libc/secure/stpcpy_chk.c
@@ -37,8 +37,6 @@
 #include <ssp/string.h>
 #undef memcpy
 
-#include "ssp_internal.h"
-
 char *
 __stpcpy_chk(char * __restrict dst, const char * __restrict src, size_t slen)
 {
diff --git a/lib/libc/secure/stpncpy_chk.c b/lib/libc/secure/stpncpy_chk.c
--- a/lib/libc/secure/stpncpy_chk.c
+++ b/lib/libc/secure/stpncpy_chk.c
@@ -37,8 +37,6 @@
 #include <ssp/string.h>
 #undef stpncpy
 
-#include "ssp_internal.h"
-
 char *
 __stpncpy_chk(char * __restrict dst, const char * __restrict src, size_t len,
     size_t slen)
diff --git a/lib/libc/secure/strcpy_chk.c b/lib/libc/secure/strcpy_chk.c
--- a/lib/libc/secure/strcpy_chk.c
+++ b/lib/libc/secure/strcpy_chk.c
@@ -37,8 +37,6 @@
 #include <ssp/string.h>
 #undef memcpy
 
-#include "ssp_internal.h"
-
 char *
 __strcpy_chk(char * __restrict dst, const char * __restrict src, size_t slen)
 {
diff --git a/lib/libc/secure/strncpy_chk.c b/lib/libc/secure/strncpy_chk.c
--- a/lib/libc/secure/strncpy_chk.c
+++ b/lib/libc/secure/strncpy_chk.c
@@ -37,8 +37,6 @@
 #include <ssp/string.h>
 #undef strncpy
 
-#include "ssp_internal.h"
-
 char *
 __strncpy_chk(char * __restrict dst, const char * __restrict src, size_t len,
     size_t slen)