diff --git a/usr.sbin/rtadvd/config.c b/usr.sbin/rtadvd/config.c
index c2d3ee2ef878..ec294f1db43a 100644
--- a/usr.sbin/rtadvd/config.c
+++ b/usr.sbin/rtadvd/config.c
@@ -258,6 +258,8 @@ getconfig(intface)
 				       __FUNCTION__);
 				exit(1);
 			}
+			memset(pfx, 0, sizeof(*pfx));
+
 			/* link into chain */
 			insque(pfx, &tmp->prefix);