Boost.Flyweight uses long names for some internal mutexes and memory segments inside the intermodule_holder component, with the purpose of guaranteeing name unicity. For instance, this is a typical name for such an internal mutex, with length 87: boost_flyweight_intermodule_holder_mutex_5660_601342046_2913549788_3054690985_591945496 However, on some platforms line NetBSD 87 chars is too much: