Qmake contains() regex is not matched

The following minimal example is used to trigger actions by a HEADER matched by a filter string.

However, the regex

 .*$$filter.*

does not work, where it should match the suffix 

.h

If I try explicitely 

.*$$filter\..*

to escape only the dot, the remaining 

h

is again matched correctly.

Is this a bug, or how can I form that regex to match any characters after the filter string?

HEADERS += foo.h bar.h

FILTER = foo bar

for(header, $$list($$HEADERS)) {
	for(filter,$$list($$FILTER)){
		message(header: $$header)
		message(filter: $$filter)
                contains(header,.*$$filter.*){      # does not work
		# contains(header,.*$$filter\..*){ # works
			message(match)
		}
	}
}