Lex&Yacc and qmake

Having problems with builds and qmake. I have set an objects_dir, like so:

OBJECTS_DIR = obj

But it seems that flex and yacc will put the object files in the same directory as the .l and .y files. Naturally when I try to link, it reports that ./obj\parser_lex.o not found.

Is there any way around this?

It's ok now. It's really hard to tell what is a problem with my makefiles and what is in the lexer or parse file.