awk: searching for non-breaking-space

This code shal search for the non-breaking space 0xA0 though it returns the error "fatal: attempt to use scalar 'nbs' as array" Can somebody help?

awk --non-decimal-data -v nbs="0xA0" '{if($0 in nbs) {print FILENAME, NR}}' *.txt

Try this:

awk '/\xA0/ { print FILENAME, FNR }' *.txt