diff --git a/lib/cpp/src/protocol/TProtocol.h b/lib/cpp/src/protocol/TProtocol.h
index 37d0801..0c513d1 100644
--- a/lib/cpp/src/protocol/TProtocol.h
+++ b/lib/cpp/src/protocol/TProtocol.h
@@ -97,7 +97,8 @@
 enum TMessageType {
   T_CALL       = 1,
   T_REPLY      = 2,
-  T_EXCEPTION  = 3
+  T_EXCEPTION  = 3,
+  T_ONEWAY     = 4
 };
 
 /**