On Jan 9, 2011, at 06:38, Jasper Frumau wrote: > configure: error: --with-system-nspr and --with-nspr-libs/cflags are mutually exclusive. I get the same error. Sounds like a bug in the xulrunner-devel port to me. Like all port bugs, please report this in the issue tracker: http://guide.macports.org/chunked/project.html