In the PSDK HRESULT_FROM_WIN32() is now an inline function, and it is __HRESULT_FROM_WIN32() which is a macro.
diff --git a/include/winnt.h b/include/winnt.h
index 04f5cf6..71dbf6d 100644
--- a/include/winnt.h
+++ b/include/winnt.h
@@ -398,10 +398,13 @@
 
 /* Misc common WIN32 types */
 typedef char            CCHAR;
-typedef LONG            HRESULT;
 typedef DWORD           LCID,       *PLCID;
 typedef WORD            LANGID;
 typedef DWORD		EXECUTION_STATE;
+#ifndef _HRESULT_DEFINED
+#define _HRESULT_DEFINED
+typedef LONG            HRESULT;
+#endif
 
 /* Handle type */