diff --git a/bip32.c b/bip32.c
index 50f1466ddb..9935bd5964 100644
--- a/bip32.c
+++ b/bip32.c
@@ -46,9 +46,6 @@
 #include "nem.h"
 #endif
 #if USE_CARDANO
-#include "ed25519-donna/modm-donna-32bit.h"
-#include "blake2b.h"
-#include "bip39.h"
 #include "pbkdf2.h"
 #endif
 #include "memzero.h"
@@ -367,8 +364,8 @@ int hdnode_private_ckd_cardano(HDNode *inout, uint32_t index)
 	return 1;
 }
 
-int hdnode_from_seed_cardano(uint8_t *pass, int pass_len, uint8_t *seed, int seed_len, HDNode *out) {
-	uint8_t secret[96];
+int hdnode_from_seed_cardano(const uint8_t *pass, int pass_len, const uint8_t *seed, int seed_len, HDNode *out) {
+	static CONFIDENTIAL uint8_t secret[96];
 	pbkdf2_hmac_sha512(pass, pass_len, seed, seed_len, 4096, secret, 96);
 	
 	secret[0] &= 248;
diff --git a/bip32.h b/bip32.h
index 2c2f799aec..8b76d65ca1 100644
--- a/bip32.h
+++ b/bip32.h
@@ -61,9 +61,10 @@ int hdnode_from_seed(const uint8_t *seed, int seed_len, const char *curve, HDNod
 #define hdnode_private_ckd_prime(X, I) hdnode_private_ckd((X), ((I) | 0x80000000))
 
 int hdnode_private_ckd(HDNode *inout, uint32_t i);
+
 #if USE_CARDANO
 int hdnode_private_ckd_cardano(HDNode *inout, uint32_t i);
-int hdnode_from_seed_cardano(uint8_t *pass, int pass_len, uint8_t *seed, int seed_len, HDNode *out);
+int hdnode_from_seed_cardano(const uint8_t *pass, int pass_len, const uint8_t *seed, int seed_len, HDNode *out);
 #endif
 
 int hdnode_public_ckd_cp(const ecdsa_curve *curve, const curve_point *parent, const uint8_t *parent_chain_code, uint32_t i, curve_point *child, uint8_t *child_chain_code);
diff --git a/tests/test_check_cardano.h b/tests/test_check_cardano.h
index 8c1f5be2a7..4c734dfad8 100644
--- a/tests/test_check_cardano.h
+++ b/tests/test_check_cardano.h
@@ -80,7 +80,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_1)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	ck_assert_mem_eq(node.chain_code,  fromhex("affbc325d9027c0f2d9f925b1dcf6c12bf5c1dd08904474066a4f2c00db56173"), 32);
 	ck_assert_mem_eq(node.private_key, fromhex("08a14df748e477a69d21c97c56db151fc19e2521f31dd0ac5360f269e5b6ea46"), 32);
@@ -97,7 +97,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_2)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	hdnode_private_ckd_cardano(&node, 0x80000000);
 
@@ -116,7 +116,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_3)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	hdnode_private_ckd_cardano(&node, 0x80000001);
 
@@ -135,7 +135,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_4)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	hdnode_private_ckd_cardano(&node, 0x80000000);
 	hdnode_private_ckd_cardano(&node, 0x80000001);
@@ -155,7 +155,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_5)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	hdnode_private_ckd_cardano(&node, 0x80000000);
 	hdnode_private_ckd_cardano(&node, 0x80000001);
@@ -176,7 +176,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_6)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	hdnode_private_ckd_cardano(&node, 0x80000000);
 	hdnode_private_ckd_cardano(&node, 0x80000001);
@@ -198,7 +198,7 @@ START_TEST(test_bip32_cardano_hdnode_vector_7)
 	uint8_t seed[66];
 	int seed_len = mnemonic_to_entropy("ring crime symptom enough erupt lady behave ramp apart settle citizen junk", seed);
 	ck_assert_int_eq(seed_len, 132);
-	hdnode_from_seed_cardano(NULL, 0, seed, seed_len / 8, &node);
+	hdnode_from_seed_cardano((const uint8_t *)"", 0, seed, seed_len / 8, &node);
 
 	hdnode_private_ckd_cardano(&node, 0x80000000);
 	hdnode_private_ckd_cardano(&node, 0x80000001);