diff --git a/electrum/tests/test_wallet_vertical.py b/electrum/tests/test_wallet_vertical.py
index dac45ff9e..ad7629827 100644
--- a/electrum/tests/test_wallet_vertical.py
+++ b/electrum/tests/test_wallet_vertical.py
@@ -2027,7 +2027,10 @@ class TestWalletOfflineSigning(TestCaseForTestnet):
         self.assertFalse(tx.is_complete())
         self.assertEqual('6a58a51591142429203b62b6ddf6b799a6926882efac229998c51bee6c3573eb', tx.txid())
         partial_tx = tx.serialize_as_bytes().hex()
-        self.assertEqual("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",
+        # note re PSBT: online wallet had put a NON-WITNESS UTXO for input0, as they did not know if it was segwit.
+        #               offline wallet now replaced this with a WITNESS-UTXO.
+        #               this switch is needed to interop with bitcoin core... https://github.com/bitcoin/bitcoin/blob/fba574c908bb61eff1a0e83c935f3526ba9035f2/src/psbt.cpp#L163
+        self.assertEqual("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",
                          partial_tx)
         tx = tx_from_any(partial_tx)  # simulates moving partial txn between cosigners
 
diff --git a/electrum/wallet.py b/electrum/wallet.py
index 47f399a1a..29a236ef6 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -1245,6 +1245,11 @@ class Abstract_Wallet(AddressSynchronizer):
             if txin.utxo is None:
                 # note: for hw wallets, for legacy inputs, ignore_network_issues used to be False
                 txin.utxo = self.get_input_tx(txin.prevout.txid.hex(), ignore_network_issues=True)
+        # If there is a NON-WITNESS UTXO, but we know input is segwit, add a WITNESS UTXO, based on it.
+        # This could have happened if previously another wallet had put a NON-WITNESS UTXO for txin,
+        # as they did not know if it was segwit. This switch is needed to interop with bitcoin core.
+        if txin.utxo and Transaction.is_segwit_input(txin):
+            txin.witness_utxo = txin.utxo.outputs()[txin.prevout.out_idx]
         txin.ensure_there_is_only_one_utxo()
 
     def _learn_derivation_path_for_address_from_txinout(self, txinout: Union[PartialTxInput, PartialTxOutput],