diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 76323255439a..f43f2d952372 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -609,7 +609,7 @@ static int tb_consumed_dp_bandwidth(struct tb *tb,
 				    int *consumed_up,
 				    int *consumed_down)
 {
-	int group_reserved[MAX_GROUPS] = {};
+	int group_reserved[MAX_GROUPS + 1] = {};
 	struct tb_cm *tcm = tb_priv(tb);
 	struct tb_tunnel *tunnel;
 	bool downstream;