diff --git a/sys/dev/virtual/virtio/balloon/virtio_balloon.c b/sys/dev/virtual/virtio/balloon/virtio_balloon.c
--- a/sys/dev/virtual/virtio/balloon/virtio_balloon.c
+++ b/sys/dev/virtual/virtio/balloon/virtio_balloon.c
@@ -471,7 +471,7 @@
 vtballoon_update_stat(struct vtballoon_softc *sc, int idx,
 	uint16_t tag, uint64_t val)
 {
-	KASSERT(idx >= VTBALLOON_S_NR, ("Stats index out of bounds"));
+	KASSERT(idx < VTBALLOON_S_NR, ("Stats index out of bounds"));
 	/*
 	 * XXX: Required for endianess in the future
 	 * sc->vtballoon_stats[idx].tag = virtio_is_little_endian(sc->vtballoon_dev) ? le16toh(tag) : tag;