Updated notes about building with the Windows 8 SDK: Get the DirectX SDK.
diff --git a/src/audio/xaudio2/SDL_xaudio2.c b/src/audio/xaudio2/SDL_xaudio2.c
index 557c3bb..504a420 100644
--- a/src/audio/xaudio2/SDL_xaudio2.c
+++ b/src/audio/xaudio2/SDL_xaudio2.c
@@ -32,7 +32,11 @@
/* The configure script already did any necessary checking */
# define SDL_XAUDIO2_HAS_SDK 1
#else
-#include <dxsdkver.h> /* XAudio2 exists as of the March 2008 DirectX SDK */
+/* XAudio2 exists as of the March 2008 DirectX SDK
+ The XAudio2 implementation available in the Windows 8 SDK targets Windows 8 and newer.
+ If you want to build SDL with XAudio2 support you should install the DirectX SDK.
+ */
+#include <dxsdkver.h>
#if (!defined(_DXSDK_BUILD_MAJOR) || (_DXSDK_BUILD_MAJOR < 1284))
# pragma message("Your DirectX SDK is too old. Disabling XAudio2 support.")
#else