According to tradition, the first Buddhist nun, Mahāprajāpatī, accepted eight fundamental rules as a condition for her ordination. One of these rules says that a full ordination ceremony, for a nun, must be carried out in both orders: first in the nuns’ order, and then in the monks’ order. Both orders need to be represented by a quorum of legal witnesses. It implies that in the absence of such a quorum, an ordination cannot be legally held, in vinaya terms. This was a major problem in fifth century China, when, as a result of a wave of vinaya translations, monastics became aware of many detailed legal issues, including the rule on a dual ordination for nuns. Since the first Buddhist nuns in China were ordained in the presence of monks only, doubt was raised on the validity of the Chinese nuns’ lineage. The discussion came to an end, however, when in ca. 433 a so-called ‘second ordination ceremony’ could be held, now in the presence of a sufficient number of Sinhalese nun witnesses. Today, a similar issue is raised again, since in two of the three active Buddhist ordination traditions, nuns arguably cannot be legally ordained due to the absence of a nuns’ order of that particular tradition to provide a legal quorum of witnesses. In the present-day debates on the possible (re-)introduction of a nuns’ lineage in both these traditions, the historic case of the fifth century Chinese nuns is often referred to. The present article examines firstly in which ways technical issues discussed fifteen centuries ago lingered on among the most prominent Chinese vinaya masters, and secondly how these same issues still fuel and influence present-day discussions.