pkgsrc-users: exporting variables from mk.conf

Subject: exporting variables from mk.conf
To: None <pkgsrc-users@netbsd.org>
From: Raymond Meyer <raymond.meyer@rambler.ru>
List: pkgsrc-users
Date: 08/20/2006 03:36:45

Hi, is there a way to export environment variables from mk.conf file? 
I tried setting 

MAKE_ENV+=MYVAR="Some value"

but it doesn't seem to work