diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 8fd74a7501d4..ac9fb336c80f 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -546,7 +546,7 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
 
 		seed = early_memremap(efi.rng_seed, sizeof(*seed));
 		if (seed != NULL) {
-			size = READ_ONCE(seed->size);
+			size = min(seed->size, EFI_RANDOM_SEED_SIZE);
 			early_memunmap(seed, sizeof(*seed));
 		} else {
 			pr_err("Could not map UEFI random seed!\n");
diff --git a/include/linux/efi.h b/include/linux/efi.h
index f9b9f9a2fd4a..880cd86c829d 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1715,7 +1715,7 @@ efi_status_t efi_exit_boot_services(efi_system_table_t *sys_table,
 				    void *priv,
 				    efi_exit_boot_map_processing priv_func);
 
-#define EFI_RANDOM_SEED_SIZE		64U
+#define EFI_RANDOM_SEED_SIZE		32U // BLAKE2S_HASH_SIZE
 
 struct linux_efi_random_seed {
 	u32	size;