diff --git a/src/ntbtls.m4 b/src/ntbtls.m4
index 55de483..fff4256 100644
--- a/src/ntbtls.m4
+++ b/src/ntbtls.m4
@@ -1,163 +1,163 @@
 dnl Autoconf macros for NTBTLS
 dnl Copyright (C) 2002, 2004, 2011 Free Software Foundation, Inc.
 dnl
 dnl This file is free software; as a special exception the author gives
 dnl unlimited permission to copy and/or distribute it, with or without
 dnl modifications, as long as this notice is preserved.
 dnl
 dnl This file is distributed in the hope that it will be useful, but
 dnl WITHOUT ANY WARRANTY, to the extent permitted by law; without even the
 dnl implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 dnl
-dnl Last-changed: 2020-11-18
+dnl Last-changed: 2022-11-01
 
 
 dnl AM_PATH_NTBTLS([MINIMUM-VERSION,
 dnl                   [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND ]]])
 dnl
 dnl Test for NTBTLS and define NTBTLS_CFLAGS and NTBTLS_LIBS.
 dnl MINIMUN-VERSION is a string with the version number optionalliy prefixed
 dnl with the API version to also check the API compatibility. Example:
 dnl a MINIMUN-VERSION of 1:1.2.5 won't pass the test unless the installed
 dnl version of libgcrypt is at least 1.2.5 *and* the API number is 1.  Using
 dnl this features allows to prevent build against newer versions of libgcrypt
 dnl with a changed API.
 dnl
 AC_DEFUN([AM_PATH_NTBTLS],
 [ AC_REQUIRE([AC_CANONICAL_HOST])
   AC_ARG_WITH(ntbtls-prefix,
             AS_HELP_STRING([--with-ntbtls-prefix=PFX],
                            [prefix where NTBTLS is installed (optional)]),
      ntbtls_config_prefix="$withval", ntbtls_config_prefix="")
   if test x"${NTBTLS_CONFIG}" = x ; then
      if test x"${ntbtls_config_prefix}" != x ; then
         NTBTLS_CONFIG="${ntbtls_config_prefix}/bin/ntbtls-config"
      fi
   fi
 
   use_gpgrt_config=""
-  if test x"${NTBTLS_CONFIG}" = x -a x"$GPGRT_CONFIG" != x -a "$GPGRT_CONFIG" != "no"; then
+  if test x"$GPGRT_CONFIG" != x -a "$GPGRT_CONFIG" != "no"; then
     if $GPGRT_CONFIG ntbtls --exists; then
       NTBTLS_CONFIG="$GPGRT_CONFIG ntbtls"
       AC_MSG_NOTICE([Use gpgrt-config as ntbtls-config])
       use_gpgrt_config=yes
     fi
   fi
   if test -z "$use_gpgrt_config"; then
     if test x"${NTBTLS_CONFIG}" = x ; then
       case "${SYSROOT}" in
         /*)
           if test -x "${SYSROOT}/bin/ntbtls-config" ; then
             NTBTLS_CONFIG="${SYSROOT}/bin/ntbtls-config"
           fi
           ;;
         '')
           ;;
          *)
           AC_MSG_WARN([Ignoring \$SYSROOT as it is not an absolute path.])
           ;;
       esac
     fi
     AC_PATH_PROG(NTBTLS_CONFIG, ntbtls-config, no)
   fi
 
   tmp=ifelse([$1], ,1:1.0.0,$1)
   if echo "$tmp" | grep ':' >/dev/null 2>/dev/null ; then
      req_ntbtls_api=`echo "$tmp"     | sed 's/\(.*\):\(.*\)/\1/'`
      min_ntbtls_version=`echo "$tmp" | sed 's/\(.*\):\(.*\)/\2/'`
   else
      req_ntbtls_api=0
      min_ntbtls_version="$tmp"
   fi
 
   AC_MSG_CHECKING(for NTBTLS - version >= $min_ntbtls_version)
   ok=no
   if test "$NTBTLS_CONFIG" != "no" ; then
     req_major=`echo $min_ntbtls_version | \
                sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\)/\1/'`
     req_minor=`echo $min_ntbtls_version | \
                sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\)/\2/'`
     req_micro=`echo $min_ntbtls_version | \
                sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\)/\3/'`
     if test -z "$use_gpgrt_config"; then
       ntbtls_config_version=`$NTBTLS_CONFIG --version`
     else
       ntbtls_config_version=`$NTBTLS_CONFIG --modversion`
     fi
     major=`echo $ntbtls_config_version | \
                sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\).*/\1/'`
     minor=`echo $ntbtls_config_version | \
                sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\).*/\2/'`
     micro=`echo $ntbtls_config_version | \
                sed 's/\([[0-9]]*\)\.\([[0-9]]*\)\.\([[0-9]]*\).*/\3/'`
     if test "$major" -gt "$req_major"; then
         ok=yes
     else
         if test "$major" -eq "$req_major"; then
             if test "$minor" -gt "$req_minor"; then
                ok=yes
             else
                if test "$minor" -eq "$req_minor"; then
                    if test "$micro" -ge "$req_micro"; then
                      ok=yes
                    fi
                fi
             fi
         fi
     fi
   fi
   if test $ok = yes; then
     AC_MSG_RESULT([yes ($ntbtls_config_version)])
   else
     AC_MSG_RESULT(no)
   fi
   if test $ok = yes; then
      # If we have a recent ntbtls, we should also check that the
      # API is compatible
      if test "$req_ntbtls_api" -gt 0 ; then
         if test -z "$use_gpgrt_config"; then
           tmp=`$NTBTLS_CONFIG --api-version 2>/dev/null || echo 0`
         else
           tmp=`$NTBTLS_CONFIG --variable=api_version 2>/dev/null || echo 0`
 	fi
         if test "$tmp" -gt 0 ; then
            AC_MSG_CHECKING([NTBTLS API version])
            if test "$req_ntbtls_api" -eq "$tmp" ; then
              AC_MSG_RESULT([okay])
            else
              ok=no
              AC_MSG_RESULT([does not match. want=$req_ntbtls_api got=$tmp])
            fi
         fi
      fi
   fi
   if test $ok = yes; then
     NTBTLS_CFLAGS=`$NTBTLS_CONFIG --cflags`
     NTBTLS_LIBS=`$NTBTLS_CONFIG --libs`
     ifelse([$2], , :, [$2])
     if test -z "$use_gpgrt_config"; then
       ntbtls_config_host=`$NTBTLS_CONFIG --host 2>/dev/null || echo none`
     else
       ntbtls_config_host=`$NTBTLS_CONFIG --variable=host 2>/dev/null || echo none`
     fi
     if test x"$ntbtls_config_host" != xnone ; then
       if test x"$ntbtls_config_host" != x"$host" ; then
   AC_MSG_WARN([[
 ***
 *** The config script "$NTBTLS_CONFIG" was
 *** built for $ntbtls_config_host and thus may not match the
 *** used host $host.
 *** You may want to use the configure option --with-ntbtls-prefix
 *** to specify a matching config script or use \$SYSROOT.
 ***]])
         gpg_config_script_warn="$gpg_config_script_warn ntbtls"
       fi
     fi
   else
     NTBTLS_CFLAGS=""
     NTBTLS_LIBS=""
     ifelse([$3], , :, [$3])
   fi
   AC_SUBST(NTBTLS_CFLAGS)
   AC_SUBST(NTBTLS_LIBS)
 ])