wptitle option doesn't accept strings with single quote

Short example: wptitle => "Site de l'Adullact",

Full example:

class { 'wordpress':
  settings => {
    'wp1.adullact.lan' => {
      wproot        => $_vhost_docroot,
      owner         => $_system_user,
      dbhost        => $_wp_database_host,
      dbname        => $_wp_database_name,
      dbuser        => $_wp_database_user,
      dbpasswd      => $_wp_database_password,
      wpadminuser   => $_wp_admin_user,
      wpadminpasswd => $_wp_admin_password,
      wpadminemail  => 'john.doe@adullact.org',
      locale        => 'fr_FR',
      wptitle       => "Site de l'Adullact",
}
}
}

produces the following error:

==> default: Notice: /Stage[main]/Wordpress::Site/Wordpress::Config::Option[wp1.adullact.lan > change title]/Exec[wp1.adullact.lan > update blogname]/returns: sh: 1: Syntax error: Unterminated quoted string
==> default: Error: '/usr/local/bin/wp option update blogname 'Site de l'Adullact'' returned 2 instead of one of [0]
==> default: Error: /Stage[main]/Wordpress::Site/Wordpress::Config::Option[wp1.adullact.lan > change title]/Exec[wp1.adullact.lan > update blogname]/returns: change from 'notrun' to ['0'] failed: '/usr/local/bin/wp option update blogname 'Site de l'Adullact'' returned 2 instead of one of [0]