There's an unclear comment [here](https://github.com/jmcomets/tcmalloc-rs/blob/master/src/lib.rs#L9-L10) that doesn't explain why `tc_free_sized` isn't used. The issue is well explained over at https://github.com/gperftools/gperftools/issues/1096#issuecomment-480629732. Summary: - it's less a bug from TCMalloc and more of a missed assumption that sized free can always be used - performance-wise there should be no noticeable impact (outside of micro-benchmarks) Additionally, the upgrade to C++14 brought [aligned new](https://github.com/gperftools/gperftools/blob/e9fbbf94508cd71bb023802af1c3c3ec5b05fb2f/src/gperftools/tcmalloc.h.in#L143-L146), which would be more correct to use; however under the hood both are implemented the same way (see the impl for [memalign](https://github.com/gperftools/gperftools/blob/master/src/tcmalloc.cc#L2161) and [tc_new_aligned](https://github.com/gperftools/gperftools/blob/master/src/tcmalloc.cc#L2182)), the only difference being one failing the C-fashion and the other the C++-fashion. I'll leave this open as a small internal docs issue since there's not much required.