QRegExp and *literal* Minus/Dash

[MuldeR]

How do I match a literal Minus/Dash in QRegExp?

My goal is to match a literal character, delimited by word boundaries.

This works as expected, to match a literal x:
@QRegExp test("\bx\b");@

But neither of these works to match a literal "-" character:
@QRegExp test1("\b-\b");
QRegExp test2("\b(-)\b");
QRegExp test3("\b\-\b");
QRegExp test4("\b(\-)\b");@

I think "-" shouldn't need escaping, but I tired with and without. No luck.

How do I do it correctly?

Thanks!