Compiling on OpenMCL, (both drakma itself and chunga) an error is given: "No MAKE-LOAD-FORM method is defined for [external-format stuff]".
Apparently, this is something to do with OpenMCL's handling of constants: http://www.clozure.com/pipermail/openmcl-devel/2002-December/000823.html . The constant in question is +latin-1+.
I found replacing all references to the constant with its value to work, but I'm sure there's a neater way. Rob