Using JavaScript insertBefore() to insert before a TextNode?

I have HTML like the following:

<div id="move-me">
    <a href="#">I'm a link</a>
</div>

<div id="new-parent">
    Some plain text.
</div>

I'm trying to write JavaScript that will move the entire #move-me div inside the #new-parent div, above the text, like so:

<div id="new-parent">
    <div id="move-me">
        <a href="#">I'm a link</a>
    </div>
    Some plain text.
</div>

Here's the JavaScript I have:

function moveDiv() {
    var moveable = document.getElementById('move-me');
    var newParent = document.getElementById('new-parent');
    newParent.parentNode.insertBefore(moveable, newParent.firstChild);
}

I'm using Firebug to debug, and I can see that newParent.firstChild is a TextNode, but I always receive the following error:

Node was not found" code: "8
newParent.parentNode.insertBefore(moveable, newParent.firstChild); 

It seems like insertBefore requires an element node and won't work on a text node... is that right? If so, is there another good method for doing this?

Note: I can't modify or clean up the HTML to include paragraph tags or remove white space.