diff --git a/common/protob/messages-bitcoin.proto b/common/protob/messages-bitcoin.proto
index 2b3ff3035..c6c1b7df9 100644
--- a/common/protob/messages-bitcoin.proto
+++ b/common/protob/messages-bitcoin.proto
@@ -212,8 +212,8 @@ message SignTx {
         required uint32 fee_rate = 1;                // coordination fee rate in units of 10^-6 percent
         required uint64 no_fee_threshold = 2;        // PlebsDontPayThreshold in Wasabi, the input amount above which the fee rate applies
         required uint64 min_registrable_amount = 3;  // minimum registrable output amount
-        required bytes mask_public_key = 4;          // ephemeral secp256k1 public key used for masking coinjoin_flags, 33 bytes in compressed form
-        required bytes signature = 5;                // the trusted party's signature of the CoinJoin request digest
+        optional bytes mask_public_key = 4;          // ephemeral secp256k1 public key used for masking coinjoin_flags, 33 bytes in compressed form
+        optional bytes signature = 5;                // the trusted party's signature of the CoinJoin request digest
     }
 }
 
diff --git a/core/src/trezor/messages.py b/core/src/trezor/messages.py
index 8772236bd..b6c421637 100644
--- a/core/src/trezor/messages.py
+++ b/core/src/trezor/messages.py
@@ -1005,8 +1005,8 @@ if TYPE_CHECKING:
         fee_rate: "int"
         no_fee_threshold: "int"
         min_registrable_amount: "int"
-        mask_public_key: "bytes"
-        signature: "bytes"
+        mask_public_key: "bytes | None"
+        signature: "bytes | None"
 
         def __init__(
             self,
@@ -1014,8 +1014,8 @@ if TYPE_CHECKING:
             fee_rate: "int",
             no_fee_threshold: "int",
             min_registrable_amount: "int",
-            mask_public_key: "bytes",
-            signature: "bytes",
+            mask_public_key: "bytes | None" = None,
+            signature: "bytes | None" = None,
         ) -> None:
             pass
 
diff --git a/python/src/trezorlib/messages.py b/python/src/trezorlib/messages.py
index 61ea1bb10..bde2dcf07 100644
--- a/python/src/trezorlib/messages.py
+++ b/python/src/trezorlib/messages.py
@@ -1747,8 +1747,8 @@ class CoinJoinRequest(protobuf.MessageType):
         1: protobuf.Field("fee_rate", "uint32", repeated=False, required=True),
         2: protobuf.Field("no_fee_threshold", "uint64", repeated=False, required=True),
         3: protobuf.Field("min_registrable_amount", "uint64", repeated=False, required=True),
-        4: protobuf.Field("mask_public_key", "bytes", repeated=False, required=True),
-        5: protobuf.Field("signature", "bytes", repeated=False, required=True),
+        4: protobuf.Field("mask_public_key", "bytes", repeated=False, required=False, default=None),
+        5: protobuf.Field("signature", "bytes", repeated=False, required=False, default=None),
     }
 
     def __init__(
@@ -1757,8 +1757,8 @@ class CoinJoinRequest(protobuf.MessageType):
         fee_rate: "int",
         no_fee_threshold: "int",
         min_registrable_amount: "int",
-        mask_public_key: "bytes",
-        signature: "bytes",
+        mask_public_key: Optional["bytes"] = None,
+        signature: Optional["bytes"] = None,
     ) -> None:
         self.fee_rate = fee_rate
         self.no_fee_threshold = no_fee_threshold
diff --git a/rust/trezor-client/src/protos/generated/messages_bitcoin.rs b/rust/trezor-client/src/protos/generated/messages_bitcoin.rs
index 9840875ee..ed233a050 100644
--- a/rust/trezor-client/src/protos/generated/messages_bitcoin.rs
+++ b/rust/trezor-client/src/protos/generated/messages_bitcoin.rs
@@ -3705,7 +3705,7 @@ pub mod sign_tx {
             self.min_registrable_amount = ::std::option::Option::Some(v);
         }
 
-        // required bytes mask_public_key = 4;
+        // optional bytes mask_public_key = 4;
 
         pub fn mask_public_key(&self) -> &[u8] {
             match self.mask_public_key.as_ref() {
@@ -3741,7 +3741,7 @@ pub mod sign_tx {
             self.mask_public_key.take().unwrap_or_else(|| ::std::vec::Vec::new())
         }
 
-        // required bytes signature = 5;
+        // optional bytes signature = 5;
 
         pub fn signature(&self) -> &[u8] {
             match self.signature.as_ref() {
@@ -3826,12 +3826,6 @@ pub mod sign_tx {
             if self.min_registrable_amount.is_none() {
                 return false;
             }
-            if self.mask_public_key.is_none() {
-                return false;
-            }
-            if self.signature.is_none() {
-                return false;
-            }
             true
         }
 
@@ -13416,8 +13410,8 @@ static file_descriptor_proto_data: &'static [u8] = b"\
     ify\x1a\xd2\x01\n\x0fCoinJoinRequest\x12\x19\n\x08fee_rate\x18\x01\x20\
     \x02(\rR\x07feeRate\x12(\n\x10no_fee_threshold\x18\x02\x20\x02(\x04R\x0e\
     noFeeThreshold\x124\n\x16min_registrable_amount\x18\x03\x20\x02(\x04R\
-    \x14minRegistrableAmount\x12&\n\x0fmask_public_key\x18\x04\x20\x02(\x0cR\
-    \rmaskPublicKey\x12\x1c\n\tsignature\x18\x05\x20\x02(\x0cR\tsignature\"\
+    \x14minRegistrableAmount\x12&\n\x0fmask_public_key\x18\x04\x20\x01(\x0cR\
+    \rmaskPublicKey\x12\x1c\n\tsignature\x18\x05\x20\x01(\x0cR\tsignature\"\
     \xd4\x05\n\tTxRequest\x12T\n\x0crequest_type\x18\x01\x20\x01(\x0e21.hw.t\
     rezor.messages.bitcoin.TxRequest.RequestTypeR\x0brequestType\x12T\n\x07d\
     etails\x18\x02\x20\x01(\x0b2:.hw.trezor.messages.bitcoin.TxRequest.TxReq\