Though open source advocates claim their software is often patched quickest, one BSD developer has reported a bug which has remained unpatched for at least quarter of a century.

A Swiss developer seems to have confounded the theory that open source software is the quickest to be patched, by revealing a bug in the BSD software distribution which has remained unpatched for at least 25 years.

Advocates of open source software argue that because of the large number of people working on such projects, bugs are quicker to spot and patch.

But developer Marc Balmer's efforts have seemingly proved the opposite. He reported the filesystem bug in his blog on Saturday.

"Much to my surprise, I not only found this problem in all other BSDs or BSD-derived systems like Mac OS X, but also in very old BSD versions," Balmer wrote. "The bug has been around for roughly 25 years or more."

As well as Mac OS X, the Unix-like BSD distribution has yielded a number of descendents, such as FreeBSD, NetBSD, OpenBSD, DragonFly BSD, JunOS (Juniper Networks' router operating system) and some of Sun Microsystems' early OSs.

Balmer claimed his fix has now been applied to FreeBSD, NetBSD and DragonFlyBSD and has been committed to the OpenBSD patch branches. He credited the development team behind Samba, the open source networking protocol, with finding the bug.