diff --git a/openbsc/src/gsm_data.c b/openbsc/src/gsm_data.c
index 9de4c1f..ede1c00 100644
--- a/openbsc/src/gsm_data.c
+++ b/openbsc/src/gsm_data.c
@@ -154,6 +154,9 @@
 		ts->nr = k;
 		ts->pchan = GSM_PCHAN_NONE;
 
+		ts->hopping.arfcns.data_len = sizeof(ts->hopping.arfcns_data);
+		ts->hopping.arfcns.data = ts->hopping.arfcns_data;
+
 		for (l = 0; l < TS_MAX_LCHAN; l++) {
 			struct gsm_lchan *lchan;
 			lchan = &ts->lchan[l];