Hi, I've just noticed that, in mutex.inl (boost::thread), a string argument to GetProcAddress is inproperly guarded by TEXT() macro. mutex.inl, line 27 ... GetProcAddress(kernel_module, TEXT("TryEnterCriticalSection"))); Since GetProcAddress doesn't have ANSI/Unicode versions, TEXT() should be stripped off. I'm referring to the 1.34.0 beta sources. Thanks in advance.