diff --git a/openbsc/src/libtrau/trau_mux.c b/openbsc/src/libtrau/trau_mux.c
index b8b90bd..5ae5ed7 100644
--- a/openbsc/src/libtrau/trau_mux.c
+++ b/openbsc/src/libtrau/trau_mux.c
@@ -212,6 +212,7 @@
 		}
 		frame->msg_type = GSM_TCHF_FRAME;
 		frame->callref = ue->callref;
+		msgb_put(msg, sizeof(struct gsm_data_frame) + 33);
 		trau_tx_to_mncc(ue->net, msg);
 
 		return 0;