diff --git a/drivers/soc/rockchip/sdmmc_vendor_storage.c b/drivers/soc/rockchip/sdmmc_vendor_storage.c
index ea1d9410b8eb..5c14c484cd6a 100644
--- a/drivers/soc/rockchip/sdmmc_vendor_storage.c
+++ b/drivers/soc/rockchip/sdmmc_vendor_storage.c
@@ -85,6 +85,7 @@ static int emmc_vendor_storage_init(void)
 				EMMC_VENDOR_PART_SIZE * max_index,
 				EMMC_VENDOR_PART_SIZE, 0))
 			goto error_exit;
+		g_vendor->free_size = sizeof(g_vendor->data) - g_vendor->free_offset;
 	} else {
 		memset((void *)g_vendor, 0, sizeof(*g_vendor));
 		g_vendor->version = 1;
@@ -160,8 +161,7 @@ static int emmc_vendor_write(u32 id, void *pbuf, u32 size)
 				item->size = size;
 				memcpy(&p_data[item->offset], pbuf, size);
 				g_vendor->free_offset = offset + align_size;
-				g_vendor->free_size -= (align_size -
-							alloc_size);
+				g_vendor->free_size = sizeof(g_vendor->data) - g_vendor->free_offset;
 			} else {
 				memcpy(&p_data[item->offset],
 				       pbuf,