No vent in catch can

I bought one of those nice-looking octagonal TIG-welded aluminum catch cans from Summit, and ran my overflow hose from the radiator neck to a brass elbow screwed into the bung. The can has a drain **** on the bottom... so far so good.

But the can does not have any vent fitting. So once the radiator cap starts opening under pressure, the can will also accumulate pressure quickly. Should I drill a small vent hole in the top of the can? Seems dangerous in an overheat situation since there is no place for the pressure to escape...