Form Helper: form_open with NO "/index.php" in action attribute?

Is there a supported method to to use the Form Helper's form_open method without it writing "/index.php" in the action attribute of the form tag short of manually writing the tag?

echo form_open('action') outputs:

     <form action="https://domain.tld/index.php/action" method="post" accept-charset="utf-8">

I would prefer echo form_open('action') to output:

     <form action="https://domain.tld/action" method="post" accept-charset="utf-8">

I am currently using the following workaround:

     echo str_replace('/index.php', '', form_open('action'));