diff --git a/src/Nazara/Core/Posix/ThreadImpl.hpp b/src/Nazara/Core/Posix/ThreadImpl.hpp
index 30d84d9d8..ba3d4ed84 100644
--- a/src/Nazara/Core/Posix/ThreadImpl.hpp
+++ b/src/Nazara/Core/Posix/ThreadImpl.hpp
@@ -8,8 +8,9 @@
 #define NAZARA_THREADIMPL_HPP
 
 #include <Nazara/Prerequesites.hpp>
+#include <Nazara/Core/String.hpp>
 
-#ifdef __GNUC__
+#if defined(__GNUC__) && !defined(_GNU_SOURCE)
 #define _GNU_SOURCE
 #endif
 
diff --git a/src/Nazara/Core/Win32/ThreadImpl.cpp b/src/Nazara/Core/Win32/ThreadImpl.cpp
index e59413413..cae997874 100644
--- a/src/Nazara/Core/Win32/ThreadImpl.cpp
+++ b/src/Nazara/Core/Win32/ThreadImpl.cpp
@@ -26,9 +26,12 @@ namespace Nz
 
 	ThreadImpl::ThreadImpl(Functor* functor)
 	{
-		m_handle = reinterpret_cast<HANDLE>(_beginthreadex(nullptr, 0, &ThreadImpl::ThreadProc, functor, 0, &m_threadId));
+		unsigned int threadId;
+		m_handle = reinterpret_cast<HANDLE>(_beginthreadex(nullptr, 0, &ThreadImpl::ThreadProc, functor, 0, &threadId));
 		if (!m_handle)
 			NazaraInternalError("Failed to create thread: " + Error::GetLastSystemError());
+
+		m_threadId = threadId;
 	}
 
 	void ThreadImpl::Detach()