diff --git a/lib/erl/include/thrift_constants.hrl b/lib/erl/include/thrift_constants.hrl
index 40c0c16..36eb49b 100644
--- a/lib/erl/include/thrift_constants.hrl
+++ b/lib/erl/include/thrift_constants.hrl
@@ -36,6 +36,7 @@
 -define(tMessageType_CALL, 1).
 -define(tMessageType_REPLY, 2).
 -define(tMessageType_EXCEPTION, 3).
+-define(tMessageType_ONEWAY, 4).
 
 % TApplicationException
 -define(TApplicationException_Structure,