diff --git a/SDK/INC/NT/ntdef.h b/SDK/INC/NT/ntdef.h
index 08e3a70..1074e76 100644
--- a/SDK/INC/NT/ntdef.h
+++ b/SDK/INC/NT/ntdef.h
@@ -139,6 +139,12 @@ typedef ULONGLONG *PULONGLONG;
 
 #define MAXLONGLONG  (0x7fffffffffffffff)
 
+#ifdef _WIN64
+typedef ULONGLONG ULONG_PTR;
+#else
+typedef ULONG ULONG_PTR;
+#endif
+
 //
 // Logical/boolean value types.
 //