diff --git a/lib/erl/include/thrift_constants.hrl b/lib/erl/include/thrift_constants.hrl
index 7b724a0..7cb29eb 100644
--- a/lib/erl/include/thrift_constants.hrl
+++ b/lib/erl/include/thrift_constants.hrl
@@ -57,3 +57,6 @@
 -define(TApplicationException_INVALID_TRANSFORM, 8).
 -define(TApplicationException_INVALID_PROTOCOL, 9).
 -define(TApplicationException_UNSUPPORTED_CLIENT_TYPE, 10).
+
+-define (MULTIPLEXED_SERVICE_SEPARATOR, ":").
+-define (MULTIPLEXED_ERROR_HANDLER_KEY, "error_handler").