Unknown variety of Olomouc mint mark is described in this article. The mint mark (letter O with tilde above all in ringlet) is registered on a 3-kreuzer produced by the mint-master Martin Fritsche (MKČ 928; Rumpl IV/169) in 1628. This mark still has not been documented on any coins, despite of the fact, that the summary of Moravian coinage from the seventeen century is detailed, thanks to the work by A. Rumpl and J. Rumpl.