diff --git a/fs/bcachefs/buckets_types.h b/fs/bcachefs/buckets_types.h
index c9698cdf866f..a19460a1bb7c 100644
--- a/fs/bcachefs/buckets_types.h
+++ b/fs/bcachefs/buckets_types.h
@@ -24,7 +24,7 @@ struct bucket_array {
 	u16			first_bucket;
 	size_t			nbuckets;
 	size_t			nbuckets_minus_first;
-	struct bucket		b[];
+	struct bucket		b[] __counted_by(nbuckets);
 };
 
 struct bucket_gens {