A package (1) is configured to store a powdery material (2) which is to be mixed with a solvent to form a medical solution, such as a dialysis solution. The package (1) comprises a filled cavity portion (6a) containing the powdery material (2), optionally separated into groups of different composition, and a tab portion (9) integrally formed with the filled cavity portion (6a) and being swept around the filled cavity portion (6a) so as to define a roll-up package. The tab portion (9) forms a protective barrier that shields the powdery material (2), e.g. by counteracting transport of moisture into and out of the package. The tab portion (9) may also stabilize the package. The roll-up package is compact, and simple to manufacture and handle.