diff --git a/src/server_cb.erl b/src/server_cb.erl
index 26a7ac2..862b9e7 100644
--- a/src/server_cb.erl
+++ b/src/server_cb.erl
@@ -6,6 +6,7 @@
 -include_lib("diameter_3gpp_ts29_272.hrl").
 -include_lib("osmo_gsup/include/gsup_protocol.hrl").
 
+-define(DIA_VENDOR_3GPP, 10415).
 
 %% diameter callbacks
 -export([peer_up/3, peer_down/3, pick_peer/4, prepare_request/3, prepare_retransmit/3,
@@ -180,7 +181,7 @@ gsup_pdp2dia_apn(GsupPdpInfo) ->
 -define(GMM_CAUSE_INV_MAND_INFO,	16#60).
 -define(GMM_CAUSE_PROTO_ERR_UNSPEC,	16#6f).
 
--define(EXP_RES(Foo),	#'Experimental-Result'{'Vendor-Id'=10415, 'Experimental-Result-Code'=Foo}).
+-define(EXP_RES(Exp),	#'Experimental-Result'{'Vendor-Id'=?DIA_VENDOR_3GPP, 'Experimental-Result-Code'=Exp}).
 
 %% see 29.272 Annex A/B
 -type empty_or_intl() :: [] | [integer()].