For my test I was building a unit test around some of my code that is using SQLite using CppUTest, so it's a DEBUG WIN32 console application compiled using Visual Studio. The checked heap is CppUTest's one. I believe it replaces malloc() and free() with its own wrappers to add instrumentation and guards, but it isn't replacing msize() as well, so I assume SQLite is seeing the size of the underlying allocation including the CppUTest guards. I'm now using `-DDSQLITE_WITHOUT_MSIZE`. This also makes things closer to how it'll behave on the embedded platform I'll eventually be using.