diff --git a/common/protob/messages-bitcoin.proto b/common/protob/messages-bitcoin.proto
index 6ec28d244..59b593f20 100644
--- a/common/protob/messages-bitcoin.proto
+++ b/common/protob/messages-bitcoin.proto
@@ -216,6 +216,7 @@ message TxAck {
             // optional uint32 decred_script_version = 10;                         // only for Decred  // deprecated -> only 0 is supported
             // optional bytes prev_block_hash_bip115 = 11;     // BIP-115 support dropped
             // optional uint32 prev_block_height_bip115 = 12;  // BIP-115 support dropped
+            optional bytes witness = 13;                                        // witness data, only set for EXTERNAL inputs
         }
         /**
         * Structure representing compiled transaction output
diff --git a/core/src/trezor/messages/TxInputType.py b/core/src/trezor/messages/TxInputType.py
index 1c4997f16..231f43981 100644
--- a/core/src/trezor/messages/TxInputType.py
+++ b/core/src/trezor/messages/TxInputType.py
@@ -26,6 +26,7 @@ class TxInputType(p.MessageType):
         multisig: MultisigRedeemScriptType = None,
         amount: int = None,
         decred_tree: int = None,
+        witness: bytes = None,
     ) -> None:
         self.address_n = address_n if address_n is not None else []
         self.prev_hash = prev_hash
@@ -36,6 +37,7 @@ class TxInputType(p.MessageType):
         self.multisig = multisig
         self.amount = amount
         self.decred_tree = decred_tree
+        self.witness = witness
 
     @classmethod
     def get_fields(cls) -> Dict:
@@ -49,4 +51,5 @@ class TxInputType(p.MessageType):
             7: ('multisig', MultisigRedeemScriptType, 0),
             8: ('amount', p.UVarintType, 0),
             9: ('decred_tree', p.UVarintType, 0),
+            13: ('witness', p.BytesType, 0),
         }
diff --git a/legacy/firmware/protob/messages-bitcoin.options b/legacy/firmware/protob/messages-bitcoin.options
index e444b86c3..65aa43d75 100644
--- a/legacy/firmware/protob/messages-bitcoin.options
+++ b/legacy/firmware/protob/messages-bitcoin.options
@@ -31,6 +31,7 @@ TransactionType.extra_data                                  max_size:1024
 TxInputType.address_n                                       max_count:8
 TxInputType.prev_hash                                       max_size:32
 TxInputType.script_sig                                      max_size:1650
+TxInputType.witness                                         max_size:109
 
 TxOutputType.address                                        max_size:130
 TxOutputType.address_n                                      max_count:8
diff --git a/python/src/trezorlib/messages/TxInputType.py b/python/src/trezorlib/messages/TxInputType.py
index 68f0df089..4d9a98594 100644
--- a/python/src/trezorlib/messages/TxInputType.py
+++ b/python/src/trezorlib/messages/TxInputType.py
@@ -26,6 +26,7 @@ class TxInputType(p.MessageType):
         multisig: MultisigRedeemScriptType = None,
         amount: int = None,
         decred_tree: int = None,
+        witness: bytes = None,
     ) -> None:
         self.address_n = address_n if address_n is not None else []
         self.prev_hash = prev_hash
@@ -36,6 +37,7 @@ class TxInputType(p.MessageType):
         self.multisig = multisig
         self.amount = amount
         self.decred_tree = decred_tree
+        self.witness = witness
 
     @classmethod
     def get_fields(cls) -> Dict:
@@ -49,4 +51,5 @@ class TxInputType(p.MessageType):
             7: ('multisig', MultisigRedeemScriptType, 0),
             8: ('amount', p.UVarintType, 0),
             9: ('decred_tree', p.UVarintType, 0),
+            13: ('witness', p.BytesType, 0),
         }