diff --git a/include/osmocom/gsm/i460_mux.h b/include/osmocom/gsm/i460_mux.h
index dd752db..e7ea9bd 100644
--- a/include/osmocom/gsm/i460_mux.h
+++ b/include/osmocom/gsm/i460_mux.h
@@ -62,6 +62,7 @@
 };
 
 struct osmo_i460_subchan {
+	struct osmo_i460_timeslot *ts;	/* back-pointer */
 	enum osmo_i460_rate rate;		/* 8/16/32/64k */
 	uint8_t bit_offset;		/* bit offset inside each byte of the B-channel */
 	struct osmo_i460_subchan_demux demux;