Hey, I have C++ code which works perfectly when compiled in C++ program. Now I want to call this C++ code from haskell via FFI. When doing so, I get this error in a HUnit test program: test-rf: malloc.c:2369: sysmalloc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed. Something wrong with memory allocation I guess. The code I am running is complex and not mine. But I ran gdb over the problem and the error occurs at this code: data = alloc_.allocate(capacity); gdb tells me, that capacity==2, so it does not seem to be an out of memory error. Also about alloc_, gdb tells me: (gdb) p alloc_ $3 = {<__gnu_cxx::new_allocator<unsigned int>> = {<No data fields>}, <No data fields>} The stack frames above the shown code are: #0 0x00007ffff69a8037 in raise () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ffff69ab698 in abort () from /lib/x86_64-linux-gnu/libc.so.6 #2 0x00007ffff69efb7a in ?? () from /lib/x86_64-linux-gnu/libc.so.6 #3 0x00007ffff69f306c in ?? () from /lib/x86_64-linux-gnu/libc.so.6 #4 0x00007ffff69f4580 in malloc () from /lib/x86_64-linux-gnu/libc.so.6 #5 0x00007ffff7b3666d in operator new(unsigned long) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6 #6 0x000000000040dbd0 in allocate (__n=2, this=0x7fffffff9a48) at /usr/include/c++/4.7/ext/new_allocator.h:94 So ... it seems to be something with the new_allocator ... Maybe I am doing something different than in the C++ code, but I do not know what so I am suspecting it has something to do with the haskell FFI. Any Ideas? Thanks! Nathan