Abstract: The invention relates to a method, in a filling machine, of producing a package with a top of plastic which is injection molded in the machine and is capped before the top has become configurationally stable. In the method, the capping, at least during a first introductory phase, takes place in that a cap with internal threads is rotated and the package is displaced linearly in a direction towards the cap in such a manner that it may be ensured that the relationship between the speed of rotation of the cap and the speed of displacement of the package substantially correspond to the thread pitch of the threads in the cap and in corresponding threads on the neck when the threads enter into mesh with one another.