diff --git a/reactos/include/psdk/sal.h b/reactos/include/psdk/sal.h
index f726c63f128..e3318b20ff5 100644
--- a/reactos/include/psdk/sal.h
+++ b/reactos/include/psdk/sal.h
@@ -605,7 +605,7 @@ enum __SAL_YesNo {_SAL_notpresent, _SAL_no, _SAL_maybe, _SAL_yes, _SAL_default};
 //#define _Field_size_bytes_full_(size)
 //#define _Field_size_bytes_full_opt_(size)
 #define _Field_size_bytes_opt_(size)                                _SAL2_NAME(_Field_size_bytes_opt_) _Group_(_Maybenull_ _Writable_bytes_(size))
-//#define _Field_size_bytes_part_(size, count)
+#define _Field_size_bytes_part_(size,count)                         _SAL2_NAME(_Field_size_bytes_part_) _Group_(_Notnull_ _Writable_bytes_(size) _Readable_bytes_(count))
 #define _Field_size_bytes_part_opt_(size, count)                    _SAL2_NAME(_Field_size_bytes_part_opt_) _Group_(_Maybenull_ _Writable_bytes_(size) _Readable_bytes_(count))
 //#define _Field_size_full_(size)
 //#define _Field_size_full_opt_(size)