A wireless device requests a network slice from a network by, first, identifying at least one network slice to be requested. Based on a mapping method that is specific to the wireless device, the wireless device forms a slice pseudonym for the or each network slice to be requested. The wireless device then transmits a request message to the network, wherein the request message comprises the or each slice pseudonym. The network node receives the request message sent by the wireless device, wherein the request message comprises at least one slice pseudonym. Based on a mapping method that is used by the wireless device and that is specific to the wireless device, the network node identifies at least one requested network slice from the or each received slice pseudonym. The network node then permits use of the requested network slice.