I've got a site that I'm trying to optimise for Google Page Speed.

There's a couple of issues that are still outstanding; one telling me I need to Specify a Character Set

I've tried with two separate Char Sets:

<meta http-equiv="Content-Type" content="text/html; UTF-8" />
<meta charset="UTF-8" />
...with neither passing Page Speed check.

What am I doing wrong? What is the correct Char Set for an HTML5 page?