diff --git a/sdk/xtdk/xtdefs.h b/sdk/xtdk/xtdefs.h
index 35ab789..d58f278 100644
--- a/sdk/xtdk/xtdefs.h
+++ b/sdk/xtdk/xtdefs.h
@@ -34,6 +34,7 @@
 #define MAXCHAR                                0x7F
 #define MINSHORT                               0x8000
 #define MAXSHORT                               0x7FFF
+#define MAXUSHORT                              0xFFFF
 #define MINLONG                                0x80000000
 #define MAXLONG                                0x7FFFFFFF
 #define MAXULONG                               0xFFFFFFFF