从strip_tags中排除<h3>

Question

I'm trying to simply exclude the <h3> tag in the strip_tags function. The result I'm getting is:

<h>blabla</h3>, instead of just <h3>blabla</h3>

The code:

$this->advertText = strip_tags($this->advertText, '<p><b><i><em><strong><br><ul><li><ol><dl><dd><dt><div><h3>');

So ... can anyone tell me what's wrong here?