The present invention concerns a dialysis acid precursor composition for use during preparation of a dialysis acid concentrate solution and for mixing with water and a bicarbonate containing concentrate into a ready-for-use dialysis solution. Said dialysis acid precursor composition consist of powder components comprising sodium chloride, at least one dry acid and at least one magnesium salt, and optionally potassium salt, calcium salt, and glucose. According to the invention said at least one magnesium salt and said optional glucose, are present as anhydrous components in said dialysis acid precursor composition.