diff --git a/m4/host-os.m4 b/m4/host-os.m4
index fc9d06506..d233ebc1b 100644
--- a/m4/host-os.m4
+++ b/m4/host-os.m4
@@ -30,8 +30,10 @@ AC_DEFUN([UTILS_HOST_OS],
        openbsd*)	os='OpenBSD';;
        nsk*)		os='NonStop Kernel';;
        nonstopux*)	os='NonStop-UX';;
-       netbsd*-gnu*)	os='GNU/NetBSD';;
+       netbsd*-gnu*)	os='GNU/NetBSD';; # NetBSD kernel+libc, GNU userland
        netbsd*)		os='NetBSD';;
+       knetbsd*-gnu)	os='GNU/KNetBSD';; # NetBSD kernel, GNU libc+userland
+       kfreebsd*-gnu)	os='GNU/KFreeBSD';; # FreeBSD kernel, GNU libc+userland
        msdosdjgpp*)	os='DJGPP';;
        mpeix*)		os='MPE/iX';;
        mint*)		os='MiNT';;
@@ -41,7 +43,6 @@ AC_DEFUN([UTILS_HOST_OS],
        hpux*)		os='HP-UX';;
        hiux*)		os='HI-UX';;
        gnu*)		os='GNU';;
-       freebsd*-gnu*)	os='GNU/FreeBSD';;
        freebsd*)	os='FreeBSD';;
        dgux*)		os='DG/UX';;
        bsdi*)		os='BSD/OS';;
diff --git a/m4/strndup.m4 b/m4/strndup.m4
index f2f5cfea6..80dfcc1d9 100644
--- a/m4/strndup.m4
+++ b/m4/strndup.m4
@@ -1,5 +1,5 @@
-# strndup.m4 serial 1
-dnl Copyright (C) 2002 Free Software Foundation, Inc.
+# strndup.m4 serial 2
+dnl Copyright (C) 2002, 2003 Free Software Foundation, Inc.
 dnl This file is free software, distributed under the terms of the GNU
 dnl General Public License.  As a special exception to the GNU General
 dnl Public License, this file may be distributed as part of a program
@@ -19,7 +19,6 @@ AC_DEFUN([gl_FUNC_STRNDUP],
 
 # Prerequisites of lib/strndup.c.
 AC_DEFUN([gl_PREREQ_STRNDUP], [
-  AC_REQUIRE([AC_HEADER_STDC])
   AC_CHECK_DECLS(strnlen)
 ])