diff --git a/openbsc/src/bsc_init.c b/openbsc/src/bsc_init.c
index 1dea0eb..adf37ed 100644
--- a/openbsc/src/bsc_init.c
+++ b/openbsc/src/bsc_init.c
@@ -405,7 +405,11 @@
 static int sw_activ_rep(struct msgb *mb)
 {
 	struct abis_om_fom_hdr *foh = msgb_l3(mb);
-	struct gsm_bts_trx *trx = mb->trx;
+	struct gsm_bts *bts = mb->trx->bts;
+	struct gsm_bts_trx *trx = gsm_bts_trx_num(bts, foh->obj_inst.trx_nr);
+
+	if (!trx)
+		return -ENODEV;
 
 	switch (foh->obj_class) {
 	case NM_OC_BASEB_TRANSC: