diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index e3df82d5d37a..70be9c87fb67 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -590,7 +590,7 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
 
 		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 d34e8a7ed4d5..4cd4ed34d3cb 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -1165,7 +1165,7 @@ efi_status_t efi_random_get_seed(void);
 	arch_efi_call_virt_teardown();					\
 })
 
-#define EFI_RANDOM_SEED_SIZE		64U
+#define EFI_RANDOM_SEED_SIZE		32U // BLAKE2S_HASH_SIZE
 
 struct linux_efi_random_seed {
 	u32	size;