Compile failure with GHC 7.4.2 / inaccurate version bounds

[hvr]

recent thyme releases fail to compile with GHC 7.4 even though declaring support for base >= 4.5 (but base-4.5 doesn't have GHC.Generics):

Configuring component lib from thyme-0.3.5.5
Preprocessing library thyme-0.3.5.5...

src/Data/Thyme/Calendar/WeekdayOfMonth.hs:33:8:
    Could not find module `GHC.Generics'
    It is a member of the hidden package `ghc-prim'.
    Perhaps you need to add `ghc-prim' to the build-depends in your .cabal file.
    Use -v to see a list of the files searched for.