64-bit Windows on AMD64/Intel EM64T is somewhat supported in the 7.0 and later release. A collector can be built with Microsoft Visual C++ 2005 or with mingw-w64 gcc. More testing would clearly be helpful. NT_MAKEFILE has been used in this environment. Uncomment the corresponding definitions of CPU and CVTRES_CPU variables (commenting out the ones for X86), and then type "nmake -f NT_MAKEFILE" in a Visual C++ command line window to build the dynamic library with threads support and the usual test programs. To verify that the collector is at least somewhat functional, run gctest.exe. This should create gctest.gc.log after a few seconds. Test_cpp.exe might not run correctly in case of dynamic GC linking. (It seems that we're getting wrong instances of operator new/delete in some cases.) This process is completely analogous to NT_MAKEFILE usage for the 32-bit library version. A similar procedure using NT_MAKEFILE should be usable to build the static library (see comments for CFLAGS_SPECIFIC and LINK_GC variables in NT_MAKEFILE). Note that some warnings have been explicitly turned off in the makefile. VC++ note: to suppress warnings -D_CRT_SECURE_NO_DEPRECATE is used. gcc note: -fno-strict-aliasing should be used if optimizing.