From the source:
def libraries_invalid?(libs)
libs.any? { |lib| lib.end_with?('.a', '.dylib') || lib.start_with?('lib') }
end
def _validate_libraries(libs)
if libraries_invalid?(libs)
error "A library should only be specified by its name"
end
end
So I guess you're either putting "lib" on the start of it or specifying an extension and you're not supposed to.