diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 0e0012368976..3e5861653b69 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -2655,7 +2655,7 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
 		return -ENODEV;
 
 	/* Allocate vop2 struct and its vop2_win array */
-	alloc_size = sizeof(*vop2) + sizeof(*vop2->win) * vop2_data->win_size;
+	alloc_size = struct_size(vop2, win, vop2_data->win_size);
 	vop2 = devm_kzalloc(dev, alloc_size, GFP_KERNEL);
 	if (!vop2)
 		return -ENOMEM;