Abstract: A method of assembling a modular machine on-site. The modular machine includes a first container frame including a first machine module attachable to the first container frame, and a second container frame including a second machine module releasably attachable to the second container frame. Further, the first machine module and the second machine module are connectable to each other. The method includes arranging the first container frame on top of a support. Further, the second container frame is arranged to be in contact with the first container frame, wherein alignment means of the first container frame and alignment means of the second container frame are arranged in connection with each other. Moreover, the second machine module is released from the second container frame and moved from a transportation position to a working position. Additionally, the second machine module is connected to the first machine module.