Methods, systems, and devices for wireless communications are described. In some systems, wireless devices may implement adjusted fractally enhanced kernel polar coding. An encoder may receive a number of information bits and a block size for transmission, and may append an additional number of information bits to the information bits for transmission. The encoder may perform a recursive bit allocation process to allocate the aggregate set of information bits between a set of sub-blocks based on mutual information metrics. To obtain the correct number of information bits and block size, the encoder may remove a number of information bits equal to the number of appended additional bits (e.g., from a first half of the sub-blocks), assign the remaining information bits to bit channels in each sub-block, and block puncture a set of bits (e.g., from the first half). The resulting codeword may mitigate occurrences of achievable signal-to-noise ratio (SNR) spikes.