A method, performed by at least one apparatus, is provided that includes obtaining first radio map data. The first radio map data indicates geographic positions with respect to a first coordinate system. The method also obtains second radio map data. The second radio map data indicates geographic positions with respect to a second coordinate system. The method further includes identifying a transformation between the first coordinate system and the second coordinate system and applying the identified transformation at least to a part of the first radio map data and/or the second radio map data. A corresponding apparatus and computer readable storage medium are also provided.