The "legitimate reason" is that it's scaling a signed value, that has meaning when negative. > void *get(int idx) { assert(idx <= arr.size(); return arr[idx];

The "legitimate reason" is that it's scaling a signed value, that has meaning when negative. > void *get(int idx) { assert(idx <= arr.size(); return arr[idx]; } You got problems there even if idx and arr.size() are unsigned.