diff --git a/drivers/input/keyboard/applespi.c b/drivers/input/keyboard/applespi.c
index acf34a5ff571..584289b67fb3 100644
--- a/drivers/input/keyboard/applespi.c
+++ b/drivers/input/keyboard/applespi.c
@@ -1494,8 +1494,7 @@ static void applespi_got_data(struct applespi_data *applespi)
 		size_t tp_len;
 
 		tp = &message->touchpad;
-		tp_len = sizeof(*tp) +
-			 tp->number_of_fingers * sizeof(tp->fingers[0]);
+		tp_len = struct_size(tp, fingers, tp->number_of_fingers);
 
 		if (le16_to_cpu(message->length) + 2 != tp_len) {
 			dev_warn_ratelimited(&applespi->spi->dev,