Firefox 2px table border graphic displays border as 1px

HTML

<table class="bad">
    <tr>
        <td>test</td>
    </tr>
</table>

<table class="ok">
    <tr>
        <td>test</td>
    </tr>
</table>

CSS

table {
    border-collapse: collapse;
}

table.ok {
    border: 1px solid black;
}

table.bad {
    border: 2px solid black;
}

http://jsfiddle.net/BD248/

Printing such HTML gives the same border for both tables in Firefox.

Other browsers like Chrome print a tighter border on .bad

How do I fix / fix the problem?

Setting the 3px border to .bad gives a “thick” border in Firefox that looks ugly.