diff --git a/src/debug.h b/src/debug.h
index 69a215a42..56952427c 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -32,6 +32,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #ifdef _WIN32
 	#define WIN32_LEAN_AND_MEAN
+	#ifndef _WIN32_WINNT
+		#define _WIN32_WINNT 0x0500
+	#endif
 	#include <windows.h>
 	#ifdef _MSC_VER
 		#include <eh.h>
diff --git a/src/jthread/jmutex.h b/src/jthread/jmutex.h
index 6675162a5..e528aeb4a 100644
--- a/src/jthread/jmutex.h
+++ b/src/jthread/jmutex.h
@@ -30,6 +30,9 @@
 #define JMUTEX_H
 
 #if (defined(WIN32) || defined(_WIN32_WCE))
+	#ifndef _WIN32_WINNT
+		#define _WIN32_WINNT 0x0500
+	#endif
 	#ifndef _WIN32_WCE
 		#include <process.h>
 	#endif // _WIN32_WCE
@@ -88,7 +91,7 @@ public:
 	void signal() {
 		SetEvent(hEvent);
 	}
-}
+};
 
 #else
 
diff --git a/src/porting.h b/src/porting.h
index 03d2fcbd3..d7d107340 100644
--- a/src/porting.h
+++ b/src/porting.h
@@ -40,14 +40,17 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 //#define ALIGNOF(type) offsetof (alignment_trick<type>, member)
 
 #ifdef _WIN32
+	#ifndef _WIN32_WINNT
+		#define _WIN32_WINNT 0x0500
+	#endif
 	#include <windows.h>
 	
 	#define sleep_ms(x) Sleep(x)
 #else
 	#include <unistd.h>
 	#include <stdint.h> //for uintptr_t
-
-	#if defined(linux) || defined(__linux)
+	
+	#if (defined(linux) || defined(__linux)) && !defined(_GNU_SOURCE)
 		#define _GNU_SOURCE
 	#endif