diff --git a/sound/soc/apple/mca.c b/sound/soc/apple/mca.c
index 9f64a9e74c54..3780aca71076 100644
--- a/sound/soc/apple/mca.c
+++ b/sound/soc/apple/mca.c
@@ -161,7 +161,7 @@ struct mca_data {
 	struct mutex port_mutex;
 
 	int nclusters;
-	struct mca_cluster clusters[];
+	struct mca_cluster clusters[] __counted_by(nclusters);
 };
 
 static void mca_modify(struct mca_cluster *cl, int regoffset, u32 mask, u32 val)