Please ignore my previous patch, if it ever made it through to the list. I have found 3 bugs in pool::release_memory(). I am under a bit of deadline pressure, so I'm sorry that I don't have the tuits to supply a tested patch for the tests :-). A tentative patch that fixes the bugs is appended, but it's only gotten the lightest of testing. I've tried to make the changes small, but the function is complicated enough that I'm afraid it's "no obvious bugs" rather than "obviously no bugs". Test case 1: ... block N all free Memory leak: blocks 0-(N-1) will be lost from the block list, because prev isn't being updated correctly. Test case 2: block 0 some non-free block 1 no free block 2 all free block 2 will not be deallocated, because prev_free is erroneously advanced too many times. There are other failure modes of this sort, but this is the simplest. Test case 3 (theoretical; the others happened to me block 0 some non-free ... block N (last block) chunks 0-m are free, and m+1 to the end are non-free Thus, m is the end of the freelist Crash: trying to call nextof(0).