additionalPatterns does not work

[lal12]

If I call modclean -t --patterns="default:*" -rPt it will find some amount of files. However if I run
modclean --patterns="default:*" --additional-patterns="*.h,*.c,*.cpp,*.cc,*.hpp,*.gypi,*.mk,*.Makefile,*.a,*.o,**/node_modules/*/build" -rPt no files at all will be found.