AC_DEFUN([PDNS_ENABLE_PKCS11],[
  AC_MSG_CHECKING([whether to enable PKCS11 support])
  AC_ARG_ENABLE([experimental-pkcs11],
    [AS_HELP_STRING([--enable-experimental-pkcs11],[enable experimental PKCS11 support @<:@default=no@:>@])],
    [enable_pkcs11=$enableval],
    [enable_pkcs11=no]
  )
  AC_MSG_RESULT([$enable_pkcs11])
  AM_CONDITIONAL([PKCS11], [test "x$enable_pkcs11" != "xno"])

  AS_IF([test "x$enable_pkcs11" != "xno"], [
    PKG_CHECK_MODULES([P11KIT1], [p11-kit-1],
      [
        AC_DEFINE([HAVE_P11KIT1],[1],[Define to 1 if you have p11-kit-1])
        AC_CHECK_LIB([p11-kit], [p11_kit_module_for_name], [AC_DEFINE([HAVE_P11KIT1_V2],[1],[Define to 1 if you have 0.20 or newer P11-kit])], [], [$P11KIT1_LIBS])
      ],
      [AC_MSG_ERROR([Could not find p11-kit-1])]
    )]
  )

])