diff --git a/jmclient/jmclient/payjoin.py b/jmclient/jmclient/payjoin.py
index 205be12..002311a 100644
--- a/jmclient/jmclient/payjoin.py
+++ b/jmclient/jmclient/payjoin.py
@@ -953,6 +953,8 @@ class PayjoinServer(Resource):
         # intended (note the outputs will be shuffled next!):
         outs[1]["value"] -= our_fee_bump
 
+        # TODO this only works for 2 input transactions, otherwise
+        # pure-shuffle will not be valid as per BIP78 ordering requirement.
         unsigned_payjoin_tx = btc.make_shuffled_tx(payjoin_tx_inputs, outs,
                                     version=payment_psbt.unsigned_tx.nVersion,
                                     locktime=payment_psbt.unsigned_tx.nLockTime)
@@ -970,6 +972,7 @@ class PayjoinServer(Resource):
                     inp.nSequence = inp2.nSequence
                     spent_outs.append(payment_psbt.inputs[j].utxo)
                     input_found = True
+                    sender_index = i
                     break
             if input_found:
                 continue
@@ -1007,6 +1010,11 @@ class PayjoinServer(Resource):
         assert signresult.num_inputs_final == len(receiver_utxos)
         assert not signresult.is_final
 
+        # with signing succcessful, remove the utxo field from the
+        # counterparty's input (this is required by BIP78). Note we don't
+        # do this on PSBT creation as the psbt signing code throws ValueError
+        # unless utxos are present.
+        receiver_signed_psbt.inputs[sender_index] = btc.PSBT_Input(index=sender_index)
         log.debug("Receiver signing successful. Payjoin PSBT is now:\n{}".format(
             self.wallet_service.human_readable_psbt(receiver_signed_psbt)))
         # construct txoutset for the wallet service callback; we cannot use