diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
index 3b8580bd33c1..2cf89a538b18 100644
--- a/include/linux/input/mt.h
+++ b/include/linux/input/mt.h
@@ -47,7 +47,7 @@ struct input_mt {
 	unsigned int flags;
 	unsigned int frame;
 	int *red;
-	struct input_mt_slot slots[];
+	struct input_mt_slot slots[] __counted_by(num_slots);
 };
 
 static inline void input_mt_set_value(struct input_mt_slot *slot,