Thanks Jasper,
it worked like a charm!
For future reference, I post the little tweaks to your solution that
made it working:

import Control.Arrow ((>>>), arr) --Needed for staticPageCompiler

import Hakyll

staticPageCompiler = readPageCompiler >>>
                     addDefaultFields >>>
                     arr applySelf -- Get rid of the last arrow

Thanks, and happy coding :)
Alfredo