diff --git a/include/oledb.idl b/include/oledb.idl
index 5609e219320..4e333353a5e 100644
--- a/include/oledb.idl
+++ b/include/oledb.idl
@@ -40,6 +40,7 @@ typedef ULONG_PTR DBREFCOUNT;
 typedef ULONG_PTR DB_UPARAMS;
 typedef LONG_PTR  DB_LPARAMS;
 typedef DWORD_PTR DBHASHVALUE;
+typedef LONG_PTR DB_LRESERVE;
 
 #include "dbs.idl"