Hi, Using Cabal 1.4 Branch and Cabal-install HEAD: C:\Neil\uniplate>cabal install --hugs Resolving dependencies... cabal: internal error: could not construct a valid install plan. The proposed (invalid) plan contained the following problems: Package uniplate-1.1 has an invalid configuration, in particular: the package has a dependency base >=3 but no package has been selected to sati sfy it. the package has a dependency containers -any but no package has been selected to satisfy it. the package has a dependency mtl -any but no package has been selected to sati sfy it. But doing it the old way: C:\Neil\uniplate>runhaskell Setup configure --hugs Configuring uniplate-1.1... C:\Neil\uniplate>runhaskell Setup build Preprocessing library uniplate-1.1... Building uniplate-1.1... C:\Neil\uniplate>runhaskell Setup install Installing: C:\Program Files\Haskell\hugs\packages\uniplate Registering uniplate-1.1... It seems like if cabal install is incapable of doing anything good on Hugs, it should at least try to see if it works already. Thanks Neil