diff --git a/plat/st/common/bl2_io_storage.c b/plat/st/common/bl2_io_storage.c
index 0bcfece..86795d7 100644
--- a/plat/st/common/bl2_io_storage.c
+++ b/plat/st/common/bl2_io_storage.c
@@ -56,7 +56,7 @@
 #if STM32MP_SDMMC || STM32MP_EMMC
 static struct mmc_device_info mmc_info;
 
-static uint32_t block_buffer[MMC_BLOCK_SIZE] __aligned(MMC_BLOCK_SIZE);
+static uint8_t block_buffer[MMC_BLOCK_SIZE] __aligned(MMC_BLOCK_SIZE);
 
 static io_block_dev_spec_t mmc_block_dev_spec = {
 	/* It's used as temp buffer in block driver */