[Lazarus] Conditional define via Build mode?

[Reinier Olislagers]

Hi all,

I'm trying to set a conditional symbol depending on build mode. I've got
Debug and Release build modes defined.

In code, I can do this:
  {$DEFINE DEBUG}
  {$IFDEF DEBUG}
  writeln('Debug: ' + Message);
  {$ENDIF DEBUG}

How can I set DEBUG only when in Debug build mode? I had a look at the
wiki page and the Project Options, Build Macros but I'm a bit lost.

I just added DEBUG:=1 to the Conditionals screen... but that doesn't
seem to do the trick... I've tried playing with adding macros but must
just be missing something elementary...

Thanks,
Reinier