diff --git a/src/gsm/gsm48_arfcn_range_encode.c b/src/gsm/gsm48_arfcn_range_encode.c
index 6423a9a..afe552d 100644
--- a/src/gsm/gsm48_arfcn_range_encode.c
+++ b/src/gsm/gsm48_arfcn_range_encode.c
@@ -166,6 +166,10 @@
 {
 	int max = 0;
 
+	/* don't dereference arfcns[] array if size is 0 */
+	if (size == 0)
+		return OSMO_GSM48_ARFCN_RANGE_128;
+
 	/*
 	 * Go for the easiest. And pick arfcns[0] == f0.
 	 */