--- old/src/os_cpu/windows_x86/vm/unwind_windows_x86.hpp	Sat Jun  1 09:41:34 2013
+++ new/src/os_cpu/windows_x86/vm/unwind_windows_x86.hpp	Sat Jun  1 09:41:34 2013
@@ -29,10 +29,15 @@
 #ifdef AMD64
 typedef unsigned char UBYTE;
 
+#if _MSC_VER < 1700
+
+/* Not needed for VS2012 compiler, comes from winnt.h. */
 #define UNW_FLAG_EHANDLER  0x01
 #define UNW_FLAG_UHANDLER  0x02
 #define UNW_FLAG_CHAININFO 0x04
 
+#endif
+
 // This structure is used to define an UNWIND_INFO that
 // only has an ExceptionHandler.  There are no UnwindCodes
 // declared.
@@ -59,6 +64,9 @@
 } RUNTIME_FUNCTION, *PRUNTIME_FUNCTION;
 */
 
+#if _MSC_VER < 1700
+
+/* Not needed for VS2012 compiler, comes from winnt.h. */
 typedef struct _DISPATCHER_CONTEXT {
     ULONG64 ControlPc;
     ULONG64 ImageBase;
@@ -71,6 +79,8 @@
     PVOID HandlerData;
 } DISPATCHER_CONTEXT, *PDISPATCHER_CONTEXT;
 
+#endif
+
 #if _MSC_VER < 1500
 
 /* Not needed for VS2008 compiler, comes from winnt.h. */