[Haskell-cafe] Specifying cabal sandbox flag for local package

Hello Cafe, I have a local forked package and added its path to sandboxed project with 'cabal sandbox add-source PATH'. However, to build that package I have to specify a flag to 'cabal install'. In other words I can't install it by 'cabal install --only-dependencies', but separately with 'cabal install PACKAGE -fFLAG'. Is there a way to tell cabal sandbox (or in project.cabal) to always use some flag(s) for compiling a (particular) package in local path? GHC 7.8.2, Cabal 1.20.0 Best regards, vlatko