// delete_mutation(RANDOM_BAD_MUTATION) defaults to removing a
    // random mutation if the player has no bad mutations, so any newly
    // added bad mutations need to be included here.
    const mutation_type bad_muts[] = {
        MUT_HERBIVOROUS,   MUT_CARNIVOROUS,     MUT_FRAIL,
        MUT_SLOW_HEALING,  MUT_FAST_METABOLISM, MUT_WEAK,
        MUT_DOPEY,         MUT_CLUMSY,          MUT_DEFORMED,
        MUT_TELEPORT,      MUT_SCREAM,          MUT_BERSERK,
        MUT_BLURRY_VISION, MUT_LOW_MAGIC,       MUT_DETERIORATION
    };
    bool done = false;
    for (int tries = 0; !done && tries < 100; ++tries)
    {
        mutation_type mutat = RANDOM_ELEMENT(bad_muts);
        if (you.mutation[mutat] > 0)
            done = delete_mutation(mutat, true, false, true);
    }
    if (!done)

    // Ensure that only bad mutations are removed.
    if (!delete_mutation(RANDOM_BAD_MUTATION, false, false, true, true))