diff --git a/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h b/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h
index 5a1bc6de79..f9eda27956 100644
--- a/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h
+++ b/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h
@@ -62,13 +62,17 @@ STATIC mp_obj_t mod_trezorcrypto_secp256k1_publickey(size_t n_args, const mp_obj
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorcrypto_secp256k1_publickey_obj, 1, 2, mod_trezorcrypto_secp256k1_publickey);
 
-static int ethereum_is_canonic(uint8_t v, uint8_t signature[64])
+static int ethereum_is_canonical(uint8_t v, uint8_t signature[64])
 {
-	(void) signature;
+	(void)signature;
 	return (v & 2) == 0;
 }
 
-/// def sign(secret_key: bytes, digest: bytes, compressed: bool = True, ethereum_canonical: bool = False) -> bytes:
+enum {
+    CANONICAL_SIG_ETHEREUM = 1,
+};
+
+/// def sign(secret_key: bytes, digest: bytes, compressed: bool = True, canonical: int = None) -> bytes:
 ///     '''
 ///     Uses secret key to produce the signature of the digest.
 ///     '''
@@ -77,10 +81,12 @@ STATIC mp_obj_t mod_trezorcrypto_secp256k1_sign(size_t n_args, const mp_obj_t *a
     mp_get_buffer_raise(args[0], &sk, MP_BUFFER_READ);
     mp_get_buffer_raise(args[1], &dig, MP_BUFFER_READ);
     bool compressed = (n_args < 3) || (args[2] == mp_const_true);
-    bool ethereum_canonical = (n_args > 3) && (args[3] == mp_const_true);
+    mp_int_t canonical = (n_args > 3) ? mp_obj_get_int(args[3]) : 0;
     int (*is_canonical)(uint8_t by, uint8_t sig[64]) = NULL;
-    if (ethereum_canonical) {
-        is_canonical = ethereum_is_canonic;
+    switch (canonical) {
+        case CANONICAL_SIG_ETHEREUM:
+            is_canonical = ethereum_is_canonical;
+            break;
     }
     if (sk.len != 32) {
         mp_raise_ValueError("Invalid length of secret key");
@@ -186,6 +192,7 @@ STATIC const mp_rom_map_elem_t mod_trezorcrypto_secp256k1_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_verify), MP_ROM_PTR(&mod_trezorcrypto_secp256k1_verify_obj) },
     { MP_ROM_QSTR(MP_QSTR_verify_recover), MP_ROM_PTR(&mod_trezorcrypto_secp256k1_verify_recover_obj) },
     { MP_ROM_QSTR(MP_QSTR_multiply), MP_ROM_PTR(&mod_trezorcrypto_secp256k1_multiply_obj) },
+    { MP_ROM_QSTR(MP_QSTR_CANONICAL_SIG_ETHEREUM), MP_OBJ_NEW_SMALL_INT(CANONICAL_SIG_ETHEREUM) },
 };
 STATIC MP_DEFINE_CONST_DICT(mod_trezorcrypto_secp256k1_globals, mod_trezorcrypto_secp256k1_globals_table);
 
diff --git a/src/apps/ethereum/sign_message.py b/src/apps/ethereum/sign_message.py
index 349b297c0e..e4bc7d80fa 100644
--- a/src/apps/ethereum/sign_message.py
+++ b/src/apps/ethereum/sign_message.py
@@ -24,7 +24,7 @@ async def sign_message(ctx, msg):
     address_n = msg.address_n or ()
     node = await seed.derive_node(ctx, address_n)
 
-    signature = secp256k1.sign(node.private_key(), message_digest(msg.message), False)
+    signature = secp256k1.sign(node.private_key(), message_digest(msg.message), False, secp256k1.CANONICAL_SIG_ETHEREUM)
 
     sig = EthereumMessageSignature()
     sig.address = node.ethereum_pubkeyhash()
diff --git a/src/apps/ethereum/sign_tx.py b/src/apps/ethereum/sign_tx.py
index de42dabf95..28650ce011 100644
--- a/src/apps/ethereum/sign_tx.py
+++ b/src/apps/ethereum/sign_tx.py
@@ -131,7 +131,7 @@ async def send_signature(ctx, msg: EthereumSignTx, digest):
     address_n = msg.address_n or ()
     node = await seed.derive_node(ctx, address_n)
 
-    signature = secp256k1.sign(node.private_key(), digest, False, True)
+    signature = secp256k1.sign(node.private_key(), digest, False, secp256k1.CANONICAL_SIG_ETHEREUM)
 
     req = EthereumTxRequest()
     req.signature_v = signature[0]