In a mobile electronic communication device for receiving a downlink radio link control (RLC) data block, the improvement comprising determining whether an Extension (E) bit within a header of the data block has been reset to zero, thereby denoting the existence of extension octets within the data block, summing the lengths of the extension octets, calculating the number of bytes in the data block, and discarding the data block in the event the sum of the lengths is greater than the number of bytes in the data block.