Nope, that's the whole point. You’re free to use the solidus in the HTML serialization of HTML5.

In the XHTML serialization of HTML5, the solidus isn’t required either; you can choose to close the elements instead.

The following examples are both confirming/valid HTML5 in ‘XML mode’ (they’re valid XHTML1 as well):

a) With solidus

    <img src="foo" alt="bar" />

b) Without solidus

    <img src="foo" alt="bar"></img>

Just to be clear though, in my post I was just pointing out that you don’t have to change anything in your HTML4/XHTML code to switch to HTML5, except for the DOCTYPE.