diff --git a/src/gb/gprs_ns.c b/src/gb/gprs_ns.c
index 1754501..b667998 100644
--- a/src/gb/gprs_ns.c
+++ b/src/gb/gprs_ns.c
@@ -1053,6 +1053,7 @@
 	snprintf(buf, sizeof(buf), "%s:%u",
 		 inet_ntoa(nsvc->ip.bts_addr.sin_addr),
 		 ntohs(nsvc->ip.bts_addr.sin_port));
+	buf[sizeof(buf) - 1] = '\0';
 
 	return buf;
 }