diff --git a/src/psbt.cpp b/src/psbt.cpp
index e3246c7969..ecb791d606 100644
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -24,7 +24,7 @@ bool PartiallySignedTransaction::IsNull() const
 bool PartiallySignedTransaction::Merge(const PartiallySignedTransaction& psbt)
 {
     // Prohibited to merge two PSBTs over different transactions
-    if (tx->GetHash() != psbt.tx->GetHash()) {
+    if (GetUniqueID() != psbt.GetUniqueID()) {
         return false;
     }
 
@@ -108,6 +108,23 @@ CMutableTransaction PartiallySignedTransaction::GetUnsignedTx() const
     return mtx;
 }
 
+uint256 PartiallySignedTransaction::GetUniqueID() const
+{
+    if (tx != nullopt) {
+        return tx->GetHash();
+    }
+
+    // Get the unsigned transaction
+    CMutableTransaction mtx = GetUnsignedTx();
+    // Set the locktime to 0
+    mtx.nLockTime = 0;
+    // Set the sequence numbers to 0
+    for (CTxIn& txin : mtx.vin) {
+        txin.nSequence = 0;
+    }
+    return mtx.GetHash();
+}
+
 bool PartiallySignedTransaction::AddInput(const CTxIn& txin, PSBTInput& psbtin)
 {
     if (std::find(tx->vin.begin(), tx->vin.end(), txin) != tx->vin.end()) {
diff --git a/src/psbt.h b/src/psbt.h
index 1396b28674..3855cab1b2 100644
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -743,6 +743,7 @@ struct PartiallySignedTransaction
     void CacheUnsignedTxPieces();
     bool ComputeTimeLock(uint32_t& locktime) const;
     CMutableTransaction GetUnsignedTx() const;
+    uint256 GetUniqueID() const;
     PartiallySignedTransaction() {}
     explicit PartiallySignedTransaction(const CMutableTransaction& tx);