diff --git a/library/GTP_CodecPort.ttcn b/library/GTP_CodecPort.ttcn
index a8507a6..317210e 100644
--- a/library/GTP_CodecPort.ttcn
+++ b/library/GTP_CodecPort.ttcn
@@ -15,6 +15,10 @@
 	import from GTPC_Types all;
 	import from GTPU_Types all;
 
+	modulepar {
+		SystemUnderTest mp_pl_SystemUnderTest := SGSN;
+	}
+
 	/* identifies a remote peer (sender or receiver) */
 	type record GtpPeer {
 		ConnectionId	connId,
@@ -58,7 +62,7 @@
 		out_ud.peer.connId := in_ud.connId;
 		out_ud.peer.remName := in_ud.remName;
 		out_ud.peer.remPort := in_ud.remPort;
-		out_ud.gtpc := dec_PDU_GTPC(in_ud.msg);
+		out_ud.gtpc := dec_PDU_GTPC(in_ud.msg, pl_SystemUnderTest := mp_pl_SystemUnderTest);
 	} with { extension "prototype(fast)" };