diff --git a/electrum/coinchooser.py b/electrum/coinchooser.py
index 45555039a..6366f8a87 100644
--- a/electrum/coinchooser.py
+++ b/electrum/coinchooser.py
@@ -120,7 +120,7 @@ class CoinChooserBase(Logger):
         constant_fee = fee_estimator_vb(2000) == fee_estimator_vb(200)
 
         def make_Bucket(desc: str, coins: List[PartialTxInput]):
-            witness = any(Transaction.is_segwit_input(coin, guess_for_address=True) for coin in coins)
+            witness = any(coin.is_segwit(guess_for_address=True) for coin in coins)
             # note that we're guessing whether the tx uses segwit based
             # on this single bucket
             weight = sum(Transaction.estimated_input_weight(coin, witness)
diff --git a/electrum/plugins/keepkey/keepkey.py b/electrum/plugins/keepkey/keepkey.py
index e7f5b1821..a96190a6b 100644
--- a/electrum/plugins/keepkey/keepkey.py
+++ b/electrum/plugins/keepkey/keepkey.py
@@ -53,7 +53,7 @@ class KeepKey_KeyStore(Hardware_KeyStore):
         prev_tx = {}
         for txin in tx.inputs():
             tx_hash = txin.prevout.txid.hex()
-            if txin.utxo is None and not Transaction.is_segwit_input(txin):
+            if txin.utxo is None and not txin.is_segwit():
                 raise UserFacingException(_('Missing previous tx for legacy input.'))
             prev_tx[tx_hash] = txin.utxo
 
diff --git a/electrum/plugins/ledger/ledger.py b/electrum/plugins/ledger/ledger.py
index a8bf50a56..d85a3c935 100644
--- a/electrum/plugins/ledger/ledger.py
+++ b/electrum/plugins/ledger/ledger.py
@@ -384,7 +384,7 @@ class Ledger_KeyStore(Hardware_KeyStore):
 
             redeemScript = Transaction.get_preimage_script(txin)
             txin_prev_tx = txin.utxo
-            if txin_prev_tx is None and not Transaction.is_segwit_input(txin):
+            if txin_prev_tx is None and not txin.is_segwit():
                 raise UserFacingException(_('Missing previous tx for legacy input.'))
             txin_prev_tx_raw = txin_prev_tx.serialize() if txin_prev_tx else None
             inputs.append([txin_prev_tx_raw,
diff --git a/electrum/plugins/safe_t/safe_t.py b/electrum/plugins/safe_t/safe_t.py
index 1bb04823f..c8278abad 100644
--- a/electrum/plugins/safe_t/safe_t.py
+++ b/electrum/plugins/safe_t/safe_t.py
@@ -51,7 +51,7 @@ class SafeTKeyStore(Hardware_KeyStore):
         prev_tx = {}
         for txin in tx.inputs():
             tx_hash = txin.prevout.txid.hex()
-            if txin.utxo is None and not Transaction.is_segwit_input(txin):
+            if txin.utxo is None and not txin.is_segwit():
                 raise UserFacingException(_('Missing previous tx for legacy input.'))
             prev_tx[tx_hash] = txin.utxo
 
diff --git a/electrum/transaction.py b/electrum/transaction.py
index aca0a61ad..2d49d6a33 100644
--- a/electrum/transaction.py
+++ b/electrum/transaction.py
@@ -243,6 +243,11 @@ class TxInput:
         n = vds.read_compact_size()
         return list(vds.read_bytes(vds.read_compact_size()) for i in range(n))
 
+    def is_segwit(self, *, guess_for_address=False) -> bool:
+        if self.witness not in (b'\x00', b'', None):
+            return True
+        return False
+
 
 class BCDataStream(object):
     """Workalike python implementation of Bitcoin's CDataStream class."""
@@ -635,7 +640,7 @@ class Transaction:
         assert isinstance(txin, PartialTxInput)
 
         _type = txin.script_type
-        if not cls.is_segwit_input(txin):
+        if not txin.is_segwit():
             return construct_witness([])
 
         if _type in ('address', 'unknown') and estimate_size:
@@ -650,23 +655,6 @@ class Transaction:
             return construct_witness([])
         raise UnknownTxinType(f'cannot construct witness for txin_type: {_type}')
 
-    @classmethod
-    def is_segwit_input(cls, txin: 'TxInput', *, guess_for_address=False) -> bool:
-        if txin.witness not in (b'\x00', b'', None):
-            return True
-        if not isinstance(txin, PartialTxInput):
-            return False
-        if txin.is_native_segwit() or txin.is_p2sh_segwit():
-            return True
-        if txin.is_native_segwit() is False and txin.is_p2sh_segwit() is False:
-            return False
-        if txin.witness_script:
-            return True
-        _type = txin.script_type
-        if _type == 'address' and guess_for_address:
-            _type = cls.guess_txintype_from_address(txin.address)
-        return is_segwit_script_type(_type)
-
     @classmethod
     def guess_txintype_from_address(cls, addr: Optional[str]) -> str:
         # It's not possible to tell the script type in general
@@ -771,7 +759,7 @@ class Transaction:
                                           hashOutputs=hashOutputs)
 
     def is_segwit(self, *, guess_for_address=False):
-        return any(self.is_segwit_input(txin, guess_for_address=guess_for_address)
+        return any(txin.is_segwit(guess_for_address=guess_for_address)
                    for txin in self.inputs())
 
     def invalidate_ser_cache(self):
@@ -829,7 +817,7 @@ class Transaction:
     def txid(self) -> Optional[str]:
         if self._cached_txid is None:
             self.deserialize()
-            all_segwit = all(self.is_segwit_input(x) for x in self.inputs())
+            all_segwit = all(txin.is_segwit() for txin in self.inputs())
             if not all_segwit and not self.is_complete():
                 return None
             try:
@@ -873,7 +861,7 @@ class Transaction:
         script = cls.input_script(txin, estimate_size=True)
         input_size = len(cls.serialize_input(txin, script)) // 2
 
-        if cls.is_segwit_input(txin, guess_for_address=True):
+        if txin.is_segwit(guess_for_address=True):
             witness_size = len(cls.serialize_witness(txin, estimate_size=True)) // 2
         else:
             witness_size = 1 if is_segwit_tx else 0
@@ -1200,7 +1188,7 @@ class PartialTxInput(TxInput, PSBTSection):
         # without verifying the input amount. This means, given a maliciously modified PSBT,
         # for non-segwit inputs, we might end up burning coins as miner fees.
         if for_signing and False:
-            if not Transaction.is_segwit_input(self) and self.witness_utxo:
+            if not self.is_segwit() and self.witness_utxo:
                 raise PSBTInputConsistencyFailure(f"PSBT input validation: "
                                                   f"If a witness UTXO is provided, no non-witness signature may be created")
         if self.redeem_script and self.address:
@@ -1340,7 +1328,7 @@ class PartialTxInput(TxInput, PSBTSection):
             return True
         if self.is_coinbase_input():
             return True
-        if self.script_sig is not None and not Transaction.is_segwit_input(self):
+        if self.script_sig is not None and not self.is_segwit():
             return True
         signatures = list(self.part_sigs.values())
         s = len(signatures)
@@ -1442,6 +1430,20 @@ class PartialTxInput(TxInput, PSBTSection):
             self._is_p2sh_segwit = calc_if_p2sh_segwit_now()
         return self._is_p2sh_segwit
 
+    def is_segwit(self, *, guess_for_address=False) -> bool:
+        if super().is_segwit():
+            return True
+        if self.is_native_segwit() or self.is_p2sh_segwit():
+            return True
+        if self.is_native_segwit() is False and self.is_p2sh_segwit() is False:
+            return False
+        if self.witness_script:
+            return True
+        _type = self.script_type
+        if _type == 'address' and guess_for_address:
+            _type = Transaction.guess_txintype_from_address(self.address)
+        return is_segwit_script_type(_type)
+
     def already_has_some_signatures(self) -> bool:
         """Returns whether progress has been made towards completing this input."""
         return (self.part_sigs
@@ -1790,7 +1792,7 @@ class PartialTransaction(Transaction):
             raise Exception("only SIGHASH_ALL signing is supported!")
         nHashType = int_to_hex(sighash, 4)
         preimage_script = self.get_preimage_script(txin)
-        if self.is_segwit_input(txin):
+        if txin.is_segwit():
             if bip143_shared_txdigest_fields is None:
                 bip143_shared_txdigest_fields = self._calc_bip143_shared_txdigest_fields()
             hashPrevouts = bip143_shared_txdigest_fields.hashPrevouts
diff --git a/electrum/wallet.py b/electrum/wallet.py
index 07c131e19..2efe9cb4e 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -2162,7 +2162,7 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
         if all([txin.utxo for txin in tx.inputs()]):
             return None
         # a single segwit input -> fine
-        if len(tx.inputs()) == 1 and Transaction.is_segwit_input(tx.inputs()[0]) and tx.inputs()[0].witness_utxo:
+        if len(tx.inputs()) == 1 and tx.inputs()[0].is_segwit() and tx.inputs()[0].witness_utxo:
             return None
         # coinjoin or similar
         if any([not self.is_mine(txin.address) for txin in tx.inputs()]):
@@ -2170,7 +2170,7 @@ class Abstract_Wallet(AddressSynchronizer, ABC):
                     + _("The input amounts could not be verified as the previous transactions are missing.\n"
                         "The amount of money being spent CANNOT be verified."))
         # some inputs are legacy
-        if any([not Transaction.is_segwit_input(txin) for txin in tx.inputs()]):
+        if any([not txin.is_segwit() for txin in tx.inputs()]):
             return (_("Warning") + ": "
                     + _("The fee could not be verified. Signing non-segwit inputs is risky:\n"
                         "if this transaction was maliciously modified before you sign,\n"