A closure piece for a powder syringe (1) is proposed, with a main body (33), a sealing element (35), which is arranged on the main body (33) such that it bears sealingly on a distal opening (9) of a powder syringe (1) when the closure piece (3) is arranged in its closing position on the powder syringe (1), and a channel (45), which passes through the main body (33) and the sealing element (35) and has a proximal end and distal end (47, 49). The closure piece (3) is characterized by a retaining element (51), which is designed and/or can be arranged such that, prior to actuation of the powder syringe (1), movement of powder (27) from a chamber (19) of the powder syringe into the channel (45) is prevented at least substantially, preferably completely, when the closure piece (3) is arranged in its closing position on the powder syringe (1).
