diff --git a/include/osmocom/bsc/gsm_data.h b/include/osmocom/bsc/gsm_data.h
index 5e2ceae..90ab8ea 100644
--- a/include/osmocom/bsc/gsm_data.h
+++ b/include/osmocom/bsc/gsm_data.h
@@ -894,6 +894,8 @@
 	time_t time;
 };
 
+extern struct osmo_tdef_group bsc_tdef_group[];
+
 struct gsm_network *gsm_network_init(void *ctx);
 
 struct gsm_bts *gsm_bts_num(const struct gsm_network *net, int num);