How do I use ASP.NET Login Controls when my Login.aspx is not at the root of my application?

<authentication mode="Forms">
  <forms defaultUrl="~/Default.aspx" loginUrl="~/login.aspx" timeout="1440" ></forms>
</authentication>

<?xml version="1.0"?>
<configuration>
    <system.web>
        ...
        <!--
            The <authentication> section enables configuration
            of the security authentication mode used by
            ASP.NET to identify an incoming user.
        -->
        <authentication mode="Forms">
            <forms loginUrl="~/FolderName/Login.aspx" />
        </authentication>
        ...
    </system.web>
    ...
</configuration>