diff --git a/openbsc/src/libtrau/trau_mux.c b/openbsc/src/libtrau/trau_mux.c
index 3831a80..b37c765 100644
--- a/openbsc/src/libtrau/trau_mux.c
+++ b/openbsc/src/libtrau/trau_mux.c
@@ -245,7 +245,10 @@
 		i++;
 		j++;
 	}
-	frame->msg_type = GSM_TCHF_FRAME;
+	if (tf->c_bits[11]) /* BFI */
+		frame->msg_type = GSM_BAD_FRAME;
+	else
+		frame->msg_type = GSM_TCHF_FRAME;
 	frame->callref = callref;
 	msgb_put(msg, sizeof(struct gsm_data_frame) + 33);