A method in a terminal for providing an ACK/NAK message to a base station is provided. The terminal counts the number of assigned downlink subframes detected from the base station resulting in k. The terminal then establishes whether each of a number of transport blocks comprised in the counted k downlink subframes is correctly received or not. In the case when each one of the transport blocks, comprised in the k downlink subframes is estimated as correctly received the terminal provides to the base station an encoded ACK message for the k subframes, which comprises k, the number of subframes.