In a system a map of a site is presented on a display. A user input specifying at least one path section in the map on the display is detected. A definition of the at least one path section is stored. A representation of a radio environment stored for the site is provided as positioning assistance data. The representation of the radio environment enables a determination of a location estimate for a mobile device at the site based on at least one characteristic of at least one radio signal detected by the mobile device at the site. The definition of the at least one specified path section is provided for enabling an adjustment of a determined location estimate.