A terminal device, comprising: means for transmitting, at the terminal device, a random access request in a random access procedure to a network device; means for receiving, during the random access procedure, from the network device an uplink grant for the terminal device; means for determining whether a size indicated by the uplink grant matches a size of a medium access control, MAC, protocol data unit, PDU, stored in a buffer of the terminal device; means for, if determining that the size indicated by the uplink grant mismatches the size of the medium access control protocol data unit stored in the buffer, including a medium access control sub-protocol data unit from the medium access control protocol data unit in a subsequent uplink transmission, characterized in that the means for including the medium access control sub-protocol data unit from the medium access control protocol data unit in the subsequent uplink transmission comprise: means for determining whether the random access procedure is successfully completed by receiving the uplink grant; and means for, in response to determining that the random access procedure is considered successfully completed, discarding a cell radio network temporary identifier, C-RNTI, medium access control, MAC, control element, CE, from the medium access control protocol data unit in the subsequent uplink transmission, wherein the means for determining whether the random access procedure is successfully completed comprise means for determining that the uplink grant is addressed to a cell radio network temporary identifier. means for transmitting, at the terminal device, a random access request in a random access procedure to a network device; means for receiving, during the random access procedure, from the network device an uplink grant for the terminal device; means for determining whether a size indicated by the uplink grant matches a size of a medium access control, MAC, protocol data unit, PDU, stored in a buffer of the terminal device; means for, if determining that the size indicated by the uplink grant mismatches the size of the medium access control protocol data unit stored in the buffer, including a medium access control sub-protocol data unit from the medium access control protocol data unit in a subsequent uplink transmission, characterized in that the means for including the medium access control sub-protocol data unit from the medium access control protocol data unit in the subsequent uplink transmission comprise: means for determining whether the random access procedure is successfully completed by receiving the uplink grant; and means for, in response to determining that the random access procedure is considered successfully completed, discarding a cell radio network temporary identifier, C-RNTI, medium access control, MAC, control element, CE, from the medium access control protocol data unit in the subsequent uplink transmission, wherein the means for determining whether the random access procedure is successfully completed comprise means for determining that the uplink grant is addressed to a cell radio network temporary identifier. means for determining whether the random access procedure is successfully completed by receiving the uplink grant; and means for, in response to determining that the random access procedure is considered successfully completed, discarding a cell radio network temporary identifier, C-RNTI, medium access control, MAC, control element, CE, from the medium access control protocol data unit in the subsequent uplink transmission, wherein the means for determining whether the random access procedure is successfully completed comprise means for determining that the uplink grant is addressed to a cell radio network temporary identifier.