diff --git a/core/embed/extmod/modtrezorconfig/modtrezorconfig.c b/core/embed/extmod/modtrezorconfig/modtrezorconfig.c
index 2031734e4..e56cb2ffa 100644
--- a/core/embed/extmod/modtrezorconfig/modtrezorconfig.c
+++ b/core/embed/extmod/modtrezorconfig/modtrezorconfig.c
@@ -47,7 +47,7 @@ STATIC secbool wrapped_ui_wait_callback(uint32_t wait, uint32_t progress,
 }
 
 /// def init(
-///    ui_wait_callback: Callable[[int, int, str], bool] = None
+///    ui_wait_callback: Optional[Callable[[int, int, str], bool]] = None
 /// ) -> None:
 ///     """
 ///     Initializes the storage.  Must be called before any other method is
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-aes.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-aes.h
index a9226bfbb..78af6a066 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-aes.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-aes.h
@@ -49,7 +49,12 @@ typedef struct _mp_obj_AES_t {
   uint8_t iv[AES_BLOCK_SIZE];
 } mp_obj_AES_t;
 
-/// def __init__(self, mode: int, key: bytes, iv: bytes = None) -> None:
+/// def __init__(
+///     self,
+///     mode: int,
+///     key: bytes,
+///     iv: Optional[bytes] = None,
+/// ) -> None:
 ///     """
 ///     Initialize AES context.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip32.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip32.h
index d2a554f42..8dd685ade 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip32.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip32.h
@@ -49,9 +49,9 @@ STATIC const mp_obj_type_t mod_trezorcrypto_HDNode_type;
 ///     fingerprint: int,
 ///     child_num: int,
 ///     chain_code: bytes,
-///     private_key: bytes = None,
-///     public_key: bytes = None,
-///     curve_name: str = None,
+///     private_key: Optional[bytes] = None,
+///     public_key: Optional[bytes] = None,
+///     curve_name: Optional[str] = None,
 /// ) -> None:
 ///     """
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip39.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip39.h
index 0ac9c8fc3..3873a6660 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip39.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-bip39.h
@@ -125,7 +125,7 @@ STATIC void wrapped_ui_wait_callback(uint32_t current, uint32_t total) {
 /// def seed(
 ///     mnemonic: str,
 ///     passphrase: str,
-///     callback: Callable[[int, int], None] = None,
+///     callback: Optional[Callable[[int, int], None]] = None,
 /// ) -> bytes:
 ///     """
 ///     Generate seed from mnemonic and passphrase.
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake256.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake256.h
index 423002562..54b8ec94f 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake256.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake256.h
@@ -37,7 +37,7 @@ typedef struct _mp_obj_Blake256_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Blake256_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None) -> None:
+/// def __init__(self, data: Optional[bytes] = None) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2b.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2b.h
index 4ec0124e2..47d6acadf 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2b.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2b.h
@@ -41,10 +41,10 @@ STATIC mp_obj_t mod_trezorcrypto_Blake2b_update(mp_obj_t self, mp_obj_t data);
 
 /// def __init__(
 ///     self,
-///     data: bytes = None,
+///     data: Optional[bytes] = None,
 ///     outlen: int = blake2b.digest_size,
-///     key: bytes = None,
-///     personal: bytes = None,
+///     key: Optional[bytes] = None,
+///     personal: Optional[bytes] = None,
 /// ) -> None:
 ///     """
 ///     Creates a hash context object.
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2s.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2s.h
index 3a2ca04fc..be99143ae 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2s.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-blake2s.h
@@ -41,10 +41,10 @@ STATIC mp_obj_t mod_trezorcrypto_Blake2s_update(mp_obj_t self, mp_obj_t data);
 
 /// def __init__(
 ///     self,
-///     data: bytes = None,
+///     data: Optional[bytes] = None,
 ///     outlen: int = blake2s.digest_size,
-///     key: bytes = None,
-///     personal: bytes = None,
+///     key: Optional[bytes] = None,
+///     personal: Optional[bytes] = None,
 /// ) -> None:
 ///     """
 ///     Creates a hash context object.
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-groestl.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-groestl.h
index 4fb98f230..6cadb9559 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-groestl.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-groestl.h
@@ -41,7 +41,7 @@ typedef struct _mp_obj_Groestl512_t {
 STATIC mp_obj_t mod_trezorcrypto_Groestl512_update(mp_obj_t self,
                                                    mp_obj_t data);
 
-/// def __init__(self, data: bytes = None) -> None:
+/// def __init__(self, data: Optional[bytes] = None) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-hmac.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-hmac.h
index 598505080..0a4eac8f7 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-hmac.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-hmac.h
@@ -48,7 +48,7 @@ STATIC mp_obj_t mod_trezorcrypto_Hmac_update(mp_obj_t self, mp_obj_t data);
 ///     self,
 ///     hashtype: int,
 ///     key: bytes,
-///     message: bytes = None
+///     message: Optional[bytes] = None,
 /// ) -> None:
 ///     """
 ///     Create a HMAC context.
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-pbkdf2.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-pbkdf2.h
index 85b2ec633..dd493e943 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-pbkdf2.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-pbkdf2.h
@@ -49,7 +49,7 @@ STATIC mp_obj_t mod_trezorcrypto_Pbkdf2_update(mp_obj_t self, mp_obj_t data);
 ///     prf: int,
 ///     password: bytes,
 ///     salt: bytes,
-///     iterations: int = None,
+///     iterations: Optional[int] = None,
 ///     blocknr: int = 1,
 /// ) -> None:
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-ripemd160.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-ripemd160.h
index ef8ed13b9..f893e1924 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-ripemd160.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-ripemd160.h
@@ -37,7 +37,7 @@ typedef struct _mp_obj_Ripemd160_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Ripemd160_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None) -> None:
+/// def __init__(self, data: Optional[bytes] = None) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h
index eaa615d1f..5aba55a50 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-secp256k1.h
@@ -113,7 +113,7 @@ enum {
 ///     secret_key: bytes,
 ///     digest: bytes,
 ///     compressed: bool = True,
-///     canonical: int = None,
+///     canonical: Optional[int] = None,
 /// ) -> bytes:
 ///     """
 ///     Uses secret key to produce the signature of the digest.
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha1.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha1.h
index 36e5a6a7d..841c2222b 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha1.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha1.h
@@ -37,7 +37,7 @@ typedef struct _mp_obj_Sha1_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Sha1_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None) -> None:
+/// def __init__(self, data: Optional[bytes] = None) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha256.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha256.h
index 762eaaf92..a659eb529 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha256.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha256.h
@@ -37,7 +37,7 @@ typedef struct _mp_obj_Sha256_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Sha256_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None) -> None:
+/// def __init__(self, data: Optional[bytes] = None) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-256.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-256.h
index 69f822790..62bd7e59d 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-256.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-256.h
@@ -38,7 +38,11 @@ typedef struct _mp_obj_Sha3_256_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Sha3_256_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None, keccak: bool = False) -> None:
+/// def __init__(
+///     self,
+///     data: Optional[bytes] = None,
+///     keccak: bool = False,
+/// ) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-512.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-512.h
index 8002beeff..5514b8556 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-512.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha3-512.h
@@ -38,7 +38,11 @@ typedef struct _mp_obj_Sha3_512_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Sha3_512_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None, keccak: bool = False) -> None:
+/// def __init__(
+///     self,
+///     data: Optional[bytes] = None,
+///     keccak: bool = False,
+/// ) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha512.h b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha512.h
index 5a16fd467..e84501d28 100644
--- a/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha512.h
+++ b/core/embed/extmod/modtrezorcrypto/modtrezorcrypto-sha512.h
@@ -37,7 +37,7 @@ typedef struct _mp_obj_Sha512_t {
 
 STATIC mp_obj_t mod_trezorcrypto_Sha512_update(mp_obj_t self, mp_obj_t data);
 
-/// def __init__(self, data: bytes = None) -> None:
+/// def __init__(self, data: Optional[bytes] = None) -> None:
 ///     """
 ///     Creates a hash context object.
 ///     """
diff --git a/core/embed/extmod/modtrezorui/modtrezorui-display.h b/core/embed/extmod/modtrezorui/modtrezorui-display.h
index d24100005..b0d7aea47 100644
--- a/core/embed/extmod/modtrezorui/modtrezorui-display.h
+++ b/core/embed/extmod/modtrezorui/modtrezorui-display.h
@@ -93,8 +93,8 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_bar_obj, 6, 6,
 ///     w: int,
 ///     h: int,
 ///     fgcolor: int,
-///     bgcolor: int = None,
-///     radius: int = None,
+///     bgcolor: Optional[int] = None,
+///     radius: Optional[int] = None,
 /// ) -> None:
 ///     """
 ///     Renders a rounded bar at position (x,y = upper left corner) with width w
@@ -243,8 +243,8 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_icon_obj, 6, 6,
 ///     yoffset: int,
 ///     fgcolor: int,
 ///     bgcolor: int,
-///     icon: bytes = None,
-///     iconfgcolor: int = None,
+///     icon: Optional[bytes] = None,
+///     iconfgcolor: Optional[int] = None,
 /// ) -> None:
 ///     """
 ///     Renders a rotating loader graphic.
@@ -317,8 +317,8 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorui_Display_print_obj,
 ///     font: int,
 ///     fgcolor: int,
 ///     bgcolor: int,
-///     text_offset: int = None,
-///     text_len: int = None,
+///     text_offset: Optional[int] = None,
+///     text_len: Optional[int] = None,
 /// ) -> None:
 ///     """
 ///     Renders left-aligned text at position (x,y) where x is left position and
@@ -421,8 +421,8 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_text_right_obj,
 ///     self,
 ///     text: str,
 ///     font: int,
-///     text_offset: int = None,
-///     text_len: int = None,
+///     text_offset: Optional[int] = None,
+///     text_len: Optional[int] = None,
 /// ) -> int:
 ///     """
 ///     Returns a width of text in pixels. Font font is used for rendering.
@@ -499,7 +499,7 @@ STATIC mp_obj_t mod_trezorui_Display_qrcode(size_t n_args,
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_qrcode_obj, 5,
                                            5, mod_trezorui_Display_qrcode);
 
-/// def orientation(self, degrees: int = None) -> int:
+/// def orientation(self, degrees: Optional[int] = None) -> int:
 ///     """
 ///     Sets display orientation to 0, 90, 180 or 270 degrees.
 ///     Everything needs to be redrawn again when this function is used.
@@ -524,7 +524,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_orientation_obj,
                                            1, 2,
                                            mod_trezorui_Display_orientation);
 
-/// def backlight(self, val: int = None) -> int:
+/// def backlight(self, val: Optional[int] = None) -> int:
 ///     """
 ///     Sets backlight intensity to the value specified in val.
 ///     Call without the val parameter to just perform the read of the value.
@@ -547,7 +547,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorui_Display_backlight_obj,
                                            1, 2,
                                            mod_trezorui_Display_backlight);
 
-/// def offset(self, xy: Tuple[int, int] = None) -> Tuple[int, int]:
+/// def offset(self, xy: Optional[Tuple[int, int]] = None) -> Tuple[int, int]:
 ///     """
 ///     Sets offset (x, y) for all subsequent drawing calls.
 ///     Call without the xy parameter to just perform the read of the value.
diff --git a/core/embed/extmod/modtrezorutils/modtrezorutils.c b/core/embed/extmod/modtrezorutils/modtrezorutils.c
index 5537214cd..c5bcadf2b 100644
--- a/core/embed/extmod/modtrezorutils/modtrezorutils.c
+++ b/core/embed/extmod/modtrezorutils/modtrezorutils.c
@@ -62,7 +62,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorutils_consteq_obj,
 ///     dst_ofs: int,
 ///     src: bytes,
 ///     src_ofs: int,
-///     n: int = None,
+///     n: Optional[int] = None,
 /// ) -> int:
 ///     """
 ///     Copies at most `n` bytes from `src` at offset `src_ofs` to
@@ -99,7 +99,7 @@ STATIC mp_obj_t mod_trezorutils_memcpy(size_t n_args, const mp_obj_t *args) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mod_trezorutils_memcpy_obj, 4, 5,
                                            mod_trezorutils_memcpy);
 
-/// def halt(msg: str = None) -> None:
+/// def halt(msg: Optional[str] = None) -> None:
 ///     """
 ///     Halts execution.
 ///     """
diff --git a/core/mocks/generated/trezorconfig.pyi b/core/mocks/generated/trezorconfig.pyi
index 130313732..de53e202e 100644
--- a/core/mocks/generated/trezorconfig.pyi
+++ b/core/mocks/generated/trezorconfig.pyi
@@ -3,7 +3,7 @@ from typing import *
 
 # extmod/modtrezorconfig/modtrezorconfig.c
 def init(
-   ui_wait_callback: Callable[[int, int, str], bool] = None
+   ui_wait_callback: Optional[Callable[[int, int, str], bool]] = None
 ) -> None:
     """
     Initializes the storage.  Must be called before any other method is
diff --git a/core/mocks/generated/trezorcrypto/__init__.pyi b/core/mocks/generated/trezorcrypto/__init__.pyi
index 68e270628..ff5f3c228 100644
--- a/core/mocks/generated/trezorcrypto/__init__.pyi
+++ b/core/mocks/generated/trezorcrypto/__init__.pyi
@@ -12,7 +12,12 @@ class aes:
     OFB: int
     CTR: int
 
-    def __init__(self, mode: int, key: bytes, iv: bytes = None) -> None:
+    def __init__(
+        self,
+        mode: int,
+        key: bytes,
+        iv: Optional[bytes] = None,
+    ) -> None:
         """
         Initialize AES context.
         """
@@ -36,7 +41,7 @@ class blake256:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None) -> None:
+    def __init__(self, data: Optional[bytes] = None) -> None:
         """
         Creates a hash context object.
         """
@@ -62,10 +67,10 @@ class blake2b:
 
     def __init__(
         self,
-        data: bytes = None,
+        data: Optional[bytes] = None,
         outlen: int = blake2b.digest_size,
-        key: bytes = None,
-        personal: bytes = None,
+        key: Optional[bytes] = None,
+        personal: Optional[bytes] = None,
     ) -> None:
         """
         Creates a hash context object.
@@ -92,10 +97,10 @@ class blake2s:
 
     def __init__(
         self,
-        data: bytes = None,
+        data: Optional[bytes] = None,
         outlen: int = blake2s.digest_size,
-        key: bytes = None,
-        personal: bytes = None,
+        key: Optional[bytes] = None,
+        personal: Optional[bytes] = None,
     ) -> None:
         """
         Creates a hash context object.
@@ -157,7 +162,7 @@ class groestl512:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None) -> None:
+    def __init__(self, data: Optional[bytes] = None) -> None:
         """
         Creates a hash context object.
         """
@@ -185,7 +190,7 @@ class hmac:
         self,
         hashtype: int,
         key: bytes,
-        message: bytes = None
+        message: Optional[bytes] = None,
     ) -> None:
         """
         Create a HMAC context.
@@ -215,7 +220,7 @@ class pbkdf2:
         prf: int,
         password: bytes,
         salt: bytes,
-        iterations: int = None,
+        iterations: Optional[int] = None,
         blocknr: int = 1,
     ) -> None:
         """
@@ -241,7 +246,7 @@ class ripemd160:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None) -> None:
+    def __init__(self, data: Optional[bytes] = None) -> None:
         """
         Creates a hash context object.
         """
@@ -265,7 +270,7 @@ class sha1:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None) -> None:
+    def __init__(self, data: Optional[bytes] = None) -> None:
         """
         Creates a hash context object.
         """
@@ -289,7 +294,7 @@ class sha256:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None) -> None:
+    def __init__(self, data: Optional[bytes] = None) -> None:
         """
         Creates a hash context object.
         """
@@ -313,7 +318,11 @@ class sha3_256:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None, keccak: bool = False) -> None:
+    def __init__(
+        self,
+        data: Optional[bytes] = None,
+        keccak: bool = False,
+    ) -> None:
         """
         Creates a hash context object.
         """
@@ -342,7 +351,11 @@ class sha3_512:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None, keccak: bool = False) -> None:
+    def __init__(
+        self,
+        data: Optional[bytes] = None,
+        keccak: bool = False,
+    ) -> None:
         """
         Creates a hash context object.
         """
@@ -371,7 +384,7 @@ class sha512:
     block_size: int
     digest_size: int
 
-    def __init__(self, data: bytes = None) -> None:
+    def __init__(self, data: Optional[bytes] = None) -> None:
         """
         Creates a hash context object.
         """
diff --git a/core/mocks/generated/trezorcrypto/bip32.pyi b/core/mocks/generated/trezorcrypto/bip32.pyi
index 84a116681..a1d3b54c6 100644
--- a/core/mocks/generated/trezorcrypto/bip32.pyi
+++ b/core/mocks/generated/trezorcrypto/bip32.pyi
@@ -13,9 +13,9 @@ class HDNode:
         fingerprint: int,
         child_num: int,
         chain_code: bytes,
-        private_key: bytes = None,
-        public_key: bytes = None,
-        curve_name: str = None,
+        private_key: Optional[bytes] = None,
+        public_key: Optional[bytes] = None,
+        curve_name: Optional[str] = None,
     ) -> None:
         """
         """
diff --git a/core/mocks/generated/trezorcrypto/bip39.pyi b/core/mocks/generated/trezorcrypto/bip39.pyi
index 1297f8779..615697fd9 100644
--- a/core/mocks/generated/trezorcrypto/bip39.pyi
+++ b/core/mocks/generated/trezorcrypto/bip39.pyi
@@ -42,7 +42,7 @@ def check(mnemonic: str) -> bool:
 def seed(
     mnemonic: str,
     passphrase: str,
-    callback: Callable[[int, int], None] = None,
+    callback: Optional[Callable[[int, int], None]] = None,
 ) -> bytes:
     """
     Generate seed from mnemonic and passphrase.
diff --git a/core/mocks/generated/trezorcrypto/secp256k1.pyi b/core/mocks/generated/trezorcrypto/secp256k1.pyi
index d1f4bdfd2..1a86c6590 100644
--- a/core/mocks/generated/trezorcrypto/secp256k1.pyi
+++ b/core/mocks/generated/trezorcrypto/secp256k1.pyi
@@ -22,7 +22,7 @@ def sign(
     secret_key: bytes,
     digest: bytes,
     compressed: bool = True,
-    canonical: int = None,
+    canonical: Optional[int] = None,
 ) -> bytes:
     """
     Uses secret key to produce the signature of the digest.
diff --git a/core/mocks/generated/trezorui.pyi b/core/mocks/generated/trezorui.pyi
index c0752f309..e78703ce6 100644
--- a/core/mocks/generated/trezorui.pyi
+++ b/core/mocks/generated/trezorui.pyi
@@ -40,8 +40,8 @@ class Display:
         w: int,
         h: int,
         fgcolor: int,
-        bgcolor: int = None,
-        radius: int = None,
+        bgcolor: Optional[int] = None,
+        radius: Optional[int] = None,
     ) -> None:
         """
         Renders a rounded bar at position (x,y = upper left corner) with width w
@@ -89,8 +89,8 @@ class Display:
         yoffset: int,
         fgcolor: int,
         bgcolor: int,
-        icon: bytes = None,
-        iconfgcolor: int = None,
+        icon: Optional[bytes] = None,
+        iconfgcolor: Optional[int] = None,
     ) -> None:
         """
         Renders a rotating loader graphic.
@@ -114,8 +114,8 @@ class Display:
         font: int,
         fgcolor: int,
         bgcolor: int,
-        text_offset: int = None,
-        text_len: int = None,
+        text_offset: Optional[int] = None,
+        text_len: Optional[int] = None,
     ) -> None:
         """
         Renders left-aligned text at position (x,y) where x is left position and
@@ -159,8 +159,8 @@ class Display:
         self,
         text: str,
         font: int,
-        text_offset: int = None,
-        text_len: int = None,
+        text_offset: Optional[int] = None,
+        text_len: Optional[int] = None,
     ) -> int:
         """
         Returns a width of text in pixels. Font font is used for rendering.
@@ -181,7 +181,7 @@ class Display:
         Scale determines a zoom factor.
         """
 
-    def orientation(self, degrees: int = None) -> int:
+    def orientation(self, degrees: Optional[int] = None) -> int:
         """
         Sets display orientation to 0, 90, 180 or 270 degrees.
         Everything needs to be redrawn again when this function is used.
@@ -189,13 +189,13 @@ class Display:
         value.
         """
 
-    def backlight(self, val: int = None) -> int:
+    def backlight(self, val: Optional[int] = None) -> int:
         """
         Sets backlight intensity to the value specified in val.
         Call without the val parameter to just perform the read of the value.
         """
 
-    def offset(self, xy: Tuple[int, int] = None) -> Tuple[int, int]:
+    def offset(self, xy: Optional[Tuple[int, int]] = None) -> Tuple[int, int]:
         """
         Sets offset (x, y) for all subsequent drawing calls.
         Call without the xy parameter to just perform the read of the value.
diff --git a/core/mocks/generated/trezorutils.pyi b/core/mocks/generated/trezorutils.pyi
index e89fb601f..cde11f30f 100644
--- a/core/mocks/generated/trezorutils.pyi
+++ b/core/mocks/generated/trezorutils.pyi
@@ -17,7 +17,7 @@ def memcpy(
     dst_ofs: int,
     src: bytes,
     src_ofs: int,
-    n: int = None,
+    n: Optional[int] = None,
 ) -> int:
     """
     Copies at most `n` bytes from `src` at offset `src_ofs` to
@@ -28,7 +28,7 @@ def memcpy(
 
 
 # extmod/modtrezorutils/modtrezorutils.c
-def halt(msg: str = None) -> None:
+def halt(msg: Optional[str] = None) -> None:
     """
     Halts execution.
     """
diff --git a/core/src/apps/bitcoin/addresses.py b/core/src/apps/bitcoin/addresses.py
index 50f2569db..364d7bb7e 100644
--- a/core/src/apps/bitcoin/addresses.py
+++ b/core/src/apps/bitcoin/addresses.py
@@ -12,7 +12,7 @@ from .multisig import multisig_get_pubkeys, multisig_pubkey_index
 from .scripts import output_script_multisig, output_script_native_p2wpkh_or_p2wsh
 
 if False:
-    from typing import List
+    from typing import List, Optional
     from trezor.crypto import bip32
     from trezor.messages.TxInputType import EnumTypeInputScriptType
 
@@ -21,7 +21,7 @@ def get_address(
     script_type: EnumTypeInputScriptType,
     coin: CoinInfo,
     node: bip32.HDNode,
-    multisig: MultisigRedeemScriptType = None,
+    multisig: Optional[MultisigRedeemScriptType] = None,
 ) -> str:
     if multisig:
         # Ensure that our public key is included in the multisig.
diff --git a/core/src/apps/bitcoin/keychain.py b/core/src/apps/bitcoin/keychain.py
index 9ef791931..2b9a1006b 100644
--- a/core/src/apps/bitcoin/keychain.py
+++ b/core/src/apps/bitcoin/keychain.py
@@ -63,9 +63,9 @@ PATTERN_UNCHAINED_DEPRECATED = "m/45'/coin_type'/account'/[0-1000000]/address_in
 
 def validate_path_against_script_type(
     coin: coininfo.CoinInfo,
-    msg: MsgWithAddressScriptType = None,
-    address_n: Bip32Path = None,
-    script_type: EnumTypeInputScriptType = None,
+    msg: Optional[MsgWithAddressScriptType] = None,
+    address_n: Optional[Bip32Path] = None,
+    script_type: Optional[EnumTypeInputScriptType] = None,
     multisig: bool = False,
 ) -> bool:
     patterns = []
diff --git a/core/src/apps/bitcoin/sign_tx/helpers.py b/core/src/apps/bitcoin/sign_tx/helpers.py
index a56257a46..0dbd1a05e 100644
--- a/core/src/apps/bitcoin/sign_tx/helpers.py
+++ b/core/src/apps/bitcoin/sign_tx/helpers.py
@@ -252,7 +252,7 @@ def confirm_nondefault_locktime(lock_time: int, lock_time_disabled: bool) -> Awa
     return (yield UiConfirmNonDefaultLocktime(lock_time, lock_time_disabled))
 
 
-def request_tx_meta(tx_req: TxRequest, coin: CoinInfo, tx_hash: bytes = None) -> Awaitable[PrevTx]:  # type: ignore
+def request_tx_meta(tx_req: TxRequest, coin: CoinInfo, tx_hash: Optional[bytes] = None) -> Awaitable[PrevTx]:  # type: ignore
     assert tx_req.details is not None
     tx_req.request_type = TXMETA
     tx_req.details.tx_hash = tx_hash
@@ -262,7 +262,7 @@ def request_tx_meta(tx_req: TxRequest, coin: CoinInfo, tx_hash: bytes = None) ->
 
 
 def request_tx_extra_data(  # type: ignore
-    tx_req: TxRequest, offset: int, size: int, tx_hash: bytes = None
+    tx_req: TxRequest, offset: int, size: int, tx_hash: Optional[bytes] = None
 ) -> Awaitable[bytearray]:
     assert tx_req.details is not None
     tx_req.request_type = TXEXTRADATA
@@ -287,7 +287,7 @@ def request_tx_input(tx_req: TxRequest, i: int, coin: CoinInfo, tx_hash: Optiona
     return sanitize_tx_input(ack.tx.input, coin)
 
 
-def request_tx_prev_input(tx_req: TxRequest, i: int, coin: CoinInfo, tx_hash: bytes = None) -> Awaitable[PrevInput]:  # type: ignore
+def request_tx_prev_input(tx_req: TxRequest, i: int, coin: CoinInfo, tx_hash: Optional[bytes] = None) -> Awaitable[PrevInput]:  # type: ignore
     assert tx_req.details is not None
     tx_req.request_type = TXINPUT
     tx_req.details.request_index = i
@@ -310,7 +310,7 @@ def request_tx_output(tx_req: TxRequest, i: int, coin: CoinInfo, tx_hash: Option
     return sanitize_tx_output(ack.tx.output, coin)
 
 
-def request_tx_prev_output(tx_req: TxRequest, i: int, coin: CoinInfo, tx_hash: bytes = None) -> Awaitable[PrevOutput]:  # type: ignore
+def request_tx_prev_output(tx_req: TxRequest, i: int, coin: CoinInfo, tx_hash: Optional[bytes] = None) -> Awaitable[PrevOutput]:  # type: ignore
     assert tx_req.details is not None
     tx_req.request_type = TXOUTPUT
     tx_req.details.request_index = i
diff --git a/core/src/apps/cardano/layout.py b/core/src/apps/cardano/layout.py
index 73cfebede..dba1a698b 100644
--- a/core/src/apps/cardano/layout.py
+++ b/core/src/apps/cardano/layout.py
@@ -399,7 +399,7 @@ async def show_address(
     address: str,
     address_type: EnumTypeCardanoAddressType,
     path: List[int],
-    network: str = None,
+    network: Optional[str] = None,
 ) -> bool:
     """
     Custom show_address function is needed because cardano addresses don't
diff --git a/core/src/apps/common/request_pin.py b/core/src/apps/common/request_pin.py
index bc38209b5..535013101 100644
--- a/core/src/apps/common/request_pin.py
+++ b/core/src/apps/common/request_pin.py
@@ -25,7 +25,7 @@ def can_lock_device() -> bool:
 async def request_pin(
     ctx: wire.GenericContext,
     prompt: str = "Enter your PIN",
-    attempts_remaining: int = None,
+    attempts_remaining: Optional[int] = None,
     allow_cancel: bool = True,
 ) -> str:
     await button_request(ctx, code=ButtonRequestType.PinEntry)
diff --git a/core/src/apps/common/seed.py b/core/src/apps/common/seed.py
index 81f5003b0..218e00f5f 100644
--- a/core/src/apps/common/seed.py
+++ b/core/src/apps/common/seed.py
@@ -6,6 +6,8 @@ from . import mnemonic
 from .passphrase import get as get_passphrase
 
 if False:
+    from typing import Optional
+
     from .paths import Bip32Path, Slip21Path
 
 
@@ -15,7 +17,9 @@ class Slip21Node:
     https://github.com/satoshilabs/slips/blob/master/slip-0021.md.
     """
 
-    def __init__(self, seed: bytes = None, data: bytes = None) -> None:
+    def __init__(
+        self, seed: Optional[bytes] = None, data: Optional[bytes] = None
+    ) -> None:
         assert seed is None or data is None, "Specify exactly one of: seed, data"
         if data is not None:
             self.data = data
diff --git a/core/src/apps/management/backup_types.py b/core/src/apps/management/backup_types.py
index 3a268b66c..cdc58e552 100644
--- a/core/src/apps/management/backup_types.py
+++ b/core/src/apps/management/backup_types.py
@@ -2,6 +2,8 @@ from trezor.crypto.slip39 import Share
 from trezor.messages import BackupType
 
 if False:
+    from typing import Optional
+
     from trezor.messages.ResetDevice import EnumTypeBackupType
 
 
@@ -26,7 +28,9 @@ def is_slip39_backup_type(backup_type: EnumTypeBackupType) -> bool:
     return backup_type in (BackupType.Slip39_Basic, BackupType.Slip39_Advanced)
 
 
-def infer_backup_type(is_slip39: bool, share: Share = None) -> EnumTypeBackupType:
+def infer_backup_type(
+    is_slip39: bool, share: Optional[Share] = None
+) -> EnumTypeBackupType:
     if not is_slip39:  # BIP-39
         return BackupType.Bip39
     elif not share or share.group_count < 1:  # invalid parameters
diff --git a/core/src/apps/management/recovery_device/keyboard_bip39.py b/core/src/apps/management/recovery_device/keyboard_bip39.py
index e866b6da6..04486f68c 100644
--- a/core/src/apps/management/recovery_device/keyboard_bip39.py
+++ b/core/src/apps/management/recovery_device/keyboard_bip39.py
@@ -172,7 +172,7 @@ class Bip39Keyboard(ui.Layout):
         # Word was confirmed by the user.
         raise ui.Result(word)
 
-    def edit(self, text: str, button: Button = None, index: int = 0) -> None:
+    def edit(self, text: str, button: Optional[Button] = None, index: int = 0) -> None:
         self.pending_button = button
         self.pending_index = index
 
diff --git a/core/src/apps/management/recovery_device/keyboard_slip39.py b/core/src/apps/management/recovery_device/keyboard_slip39.py
index cafa1e7b4..576064b56 100644
--- a/core/src/apps/management/recovery_device/keyboard_slip39.py
+++ b/core/src/apps/management/recovery_device/keyboard_slip39.py
@@ -170,7 +170,7 @@ class Slip39Keyboard(ui.Layout):
         # Word was confirmed by the user.
         raise ui.Result(word)
 
-    def edit(self, button: Button = None, index: int = 0) -> None:
+    def edit(self, button: Optional[Button] = None, index: int = 0) -> None:
         self.pending_button = button
         self.pending_index = index
 
diff --git a/core/src/apps/management/recovery_device/layout.py b/core/src/apps/management/recovery_device/layout.py
index 38c01af7e..d88211c72 100644
--- a/core/src/apps/management/recovery_device/layout.py
+++ b/core/src/apps/management/recovery_device/layout.py
@@ -205,7 +205,7 @@ async def show_group_threshold_reached(ctx: wire.GenericContext) -> None:
 
 
 class RecoveryHomescreen(ui.Component):
-    def __init__(self, text: str, subtext: str = None):
+    def __init__(self, text: str, subtext: Optional[str] = None):
         super().__init__()
         self.text = text
         self.subtext = subtext
@@ -248,7 +248,7 @@ async def homescreen_dialog(
     ctx: wire.GenericContext,
     homepage: RecoveryHomescreen,
     button_label: str,
-    info_func: Callable = None,
+    info_func: Optional[Callable] = None,
 ) -> None:
     while True:
         if info_func:
diff --git a/core/src/protobuf.py b/core/src/protobuf.py
index 3d7cd60c8..9cb0caba5 100644
--- a/core/src/protobuf.py
+++ b/core/src/protobuf.py
@@ -4,7 +4,18 @@ bytes, string, embedded message and repeated fields.
 """
 
 if False:
-    from typing import Any, Callable, Dict, Iterable, List, Tuple, Type, TypeVar, Union
+    from typing import (
+        Any,
+        Callable,
+        Dict,
+        Iterable,
+        List,
+        Optional,
+        Tuple,
+        Type,
+        TypeVar,
+        Union,
+    )
     from typing_extensions import Protocol
 
     class Reader(Protocol):
@@ -200,7 +211,7 @@ if False:
 def load_message(
     reader: Reader,
     msg_type: Type[LoadedMessageType],
-    field_cache: FieldCache = None,
+    field_cache: Optional[FieldCache] = None,
     experimental_enabled: bool = True,
 ) -> LoadedMessageType:
     if field_cache is None:
@@ -295,7 +306,7 @@ def load_message(
 
 
 def dump_message(
-    writer: Writer, msg: MessageType, field_cache: FieldCache = None
+    writer: Writer, msg: MessageType, field_cache: Optional[FieldCache] = None
 ) -> None:
     repvalue = [0]
 
@@ -360,7 +371,7 @@ def dump_message(
                 raise TypeError
 
 
-def count_message(msg: MessageType, field_cache: FieldCache = None) -> int:
+def count_message(msg: MessageType, field_cache: Optional[FieldCache] = None) -> int:
     nbytes = 0
     repvalue = [0]
 
diff --git a/core/src/storage/cache.py b/core/src/storage/cache.py
index 9a804f6a3..3234325d1 100644
--- a/core/src/storage/cache.py
+++ b/core/src/storage/cache.py
@@ -41,7 +41,7 @@ def _move_session_ids_queue(session_id: bytes) -> None:
     _session_ids.insert(0, session_id)
 
 
-def start_session(received_session_id: bytes = None) -> bytes:
+def start_session(received_session_id: Optional[bytes] = None) -> bytes:
     if received_session_id and received_session_id in _session_ids:
         session_id = received_session_id
     else:
diff --git a/core/src/trezor/loop.py b/core/src/trezor/loop.py
index aec59ad01..fd6bfdea6 100644
--- a/core/src/trezor/loop.py
+++ b/core/src/trezor/loop.py
@@ -59,8 +59,8 @@ TASK_CLOSED = TaskClosed()
 def schedule(
     task: Task,
     value: Any = None,
-    deadline: int = None,
-    finalizer: Finalizer = None,
+    deadline: Optional[int] = None,
+    finalizer: Optional[Finalizer] = None,
     reschedule: bool = False,
 ) -> None:
     """
@@ -322,7 +322,7 @@ class race(Syscall):
             scheduled.append(child_task)
             # TODO: document the types here
 
-    def exit(self, except_for: Task = None) -> None:
+    def exit(self, except_for: Optional[Task] = None) -> None:
         for task in self.scheduled:
             if task != except_for:
                 close(task)
diff --git a/core/src/trezor/ui/components/tt/passphrase.py b/core/src/trezor/ui/components/tt/passphrase.py
index d3c6646d8..b9610ae96 100644
--- a/core/src/trezor/ui/components/tt/passphrase.py
+++ b/core/src/trezor/ui/components/tt/passphrase.py
@@ -191,7 +191,9 @@ class PassphraseKeyboard(ui.Layout):
         # Timeout occurred, let's just reset the pending marker.
         self.edit(self.input.text)
 
-    def edit(self, text: str, button: KeyButton = None, index: int = 0) -> None:
+    def edit(
+        self, text: str, button: Optional[KeyButton] = None, index: int = 0
+    ) -> None:
         if len(text) > self.max_length:
             return
 
diff --git a/core/src/trezor/ui/components/tt/swipe.py b/core/src/trezor/ui/components/tt/swipe.py
index 90451a123..45d63e6ad 100644
--- a/core/src/trezor/ui/components/tt/swipe.py
+++ b/core/src/trezor/ui/components/tt/swipe.py
@@ -3,7 +3,7 @@ from micropython import const
 from trezor import io, loop, ui
 
 if False:
-    from typing import Generator
+    from typing import Generator, Optional
 
 SWIPE_UP = const(0x01)
 SWIPE_DOWN = const(0x02)
@@ -18,7 +18,9 @@ _SWIPE_TRESHOLD = const(30)
 
 
 class Swipe(ui.Component):
-    def __init__(self, directions: int = SWIPE_ALL, area: ui.Area = None) -> None:
+    def __init__(
+        self, directions: int = SWIPE_ALL, area: Optional[ui.Area] = None
+    ) -> None:
         super().__init__()
         if area is None:
             area = (0, 0, ui.WIDTH, ui.HEIGHT)
diff --git a/core/src/trezor/utils.py b/core/src/trezor/utils.py
index 96bcfd9d5..73e3d24ba 100644
--- a/core/src/trezor/utils.py
+++ b/core/src/trezor/utils.py
@@ -62,7 +62,7 @@ def unimport_end(mods: Iterable[str]) -> None:
     gc.collect()
 
 
-def ensure(cond: bool, msg: str = None) -> None:
+def ensure(cond: bool, msg: Optional[str] = None) -> None:
     if not cond:
         if msg is None:
             raise AssertionError
diff --git a/core/src/trezor/wire/__init__.py b/core/src/trezor/wire/__init__.py
index 3a513926e..19303cc0d 100644
--- a/core/src/trezor/wire/__init__.py
+++ b/core/src/trezor/wire/__init__.py
@@ -123,7 +123,7 @@ if False:
 def _wrap_protobuf_load(
     reader: protobuf.Reader,
     expected_type: Type[protobuf.LoadedMessageType],
-    field_cache: protobuf.FieldCache = None,
+    field_cache: Optional[protobuf.FieldCache] = None,
 ) -> protobuf.LoadedMessageType:
     try:
         return protobuf.load_message(
@@ -169,7 +169,7 @@ class Context:
         self,
         msg: protobuf.MessageType,
         expected_type: Type[protobuf.LoadedMessageType],
-        field_cache: protobuf.FieldCache = None,
+        field_cache: Optional[protobuf.FieldCache] = None,
     ) -> protobuf.LoadedMessageType:
         await self.write(msg, field_cache)
         del msg
@@ -189,7 +189,7 @@ class Context:
     async def read(
         self,
         expected_type: Type[protobuf.LoadedMessageType],
-        field_cache: protobuf.FieldCache = None,
+        field_cache: Optional[protobuf.FieldCache] = None,
     ) -> protobuf.LoadedMessageType:
         if __debug__:
             log.debug(
@@ -256,7 +256,9 @@ class Context:
         return _wrap_protobuf_load(msg.data, exptype)
 
     async def write(
-        self, msg: protobuf.MessageType, field_cache: protobuf.FieldCache = None
+        self,
+        msg: protobuf.MessageType,
+        field_cache: Optional[protobuf.FieldCache] = None,
     ) -> None:
         if __debug__:
             log.debug(
diff --git a/setup.cfg b/setup.cfg
index 1d5a93b7b..f0a499431 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -45,7 +45,7 @@ disallow_untyped_decorators = True
 disallow_untyped_defs = True
 disallow_incomplete_defs = True
 namespace_packages = True
-# no_implicit_optional = True
+no_implicit_optional = True
 warn_redundant_casts = True
 warn_return_any = True
 warn_unused_configs = True