diff --git a/src/psbt.h b/src/psbt.h
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -505,6 +505,15 @@
                    SignatureData *out_sigdata = nullptr,
                    bool use_dummy = false);
 
+/**
+ * Updates a PSBTOutput with information from provider.
+ *
+ * This fills in the redeem_script, witness_script, and hd_keypaths where
+ * possible.
+ */
+void UpdatePSBTOutput(const SigningProvider &provider,
+                      PartiallySignedTransaction &psbt, int index);
+
 /**
  * Finalizes a PSBT if possible, combining partial signatures.
  *
diff --git a/src/psbt.cpp b/src/psbt.cpp
--- a/src/psbt.cpp
+++ b/src/psbt.cpp
@@ -5,7 +5,6 @@
 #include <psbt.h>
 #include <util/strencodings.h>
 
-
 PartiallySignedTransaction::PartiallySignedTransaction(
     const CMutableTransaction &txIn)
     : tx(txIn) {
@@ -173,6 +172,28 @@
     return !input.final_script_sig.empty();
 }
 
+void UpdatePSBTOutput(const SigningProvider &provider,
+                      PartiallySignedTransaction &psbt, int index) {
+    const CTxOut &out = psbt.tx->vout.at(index);
+    PSBTOutput &psbt_out = psbt.outputs.at(index);
+
+    // Fill a SignatureData with output info
+    SignatureData sigdata;
+    psbt_out.FillSignatureData(sigdata);
+
+    // Construct a would-be spend of this output, to update sigdata with.
+    // Note that ProduceSignature is used to fill in metadata (not actual
+    // signatures), so provider does not need to provide any private keys (it
+    // can be a HidingSigningProvider).
+    MutableTransactionSignatureCreator creator(psbt.tx.get_ptr(), /* index */ 0,
+                                               out.nValue,
+                                               SigHashType().withForkId());
+    ProduceSignature(provider, creator, out.scriptPubKey, sigdata);
+
+    // Put redeem_script and key paths, into PSBTOutput.
+    psbt_out.FromSignatureData(sigdata);
+}
+
 bool SignPSBTInput(const SigningProvider &provider,
                    PartiallySignedTransaction &psbt, int index,
                    SigHashType sighash, SignatureData *out_sigdata,
diff --git a/src/wallet/psbtwallet.cpp b/src/wallet/psbtwallet.cpp
--- a/src/wallet/psbtwallet.cpp
+++ b/src/wallet/psbtwallet.cpp
@@ -51,18 +51,8 @@
     // Fill in the bip32 keypaths and redeemscripts for the outputs so that
     // hardware wallets can identify change
     for (size_t i = 0; i < psbtx.tx->vout.size(); ++i) {
-        const CTxOut &out = psbtx.tx->vout.at(i);
-        PSBTOutput &psbt_out = psbtx.outputs.at(i);
-
-        // Fill a SignatureData with output info
-        SignatureData sigdata;
-        psbt_out.FillSignatureData(sigdata);
-
-        MutableTransactionSignatureCreator creator(
-            psbtx.tx.get_ptr(), 0, out.nValue, SigHashType().withForkId());
-        ProduceSignature(HidingSigningProvider(pwallet, true, !bip32derivs),
-                         creator, out.scriptPubKey, sigdata);
-        psbt_out.FromSignatureData(sigdata);
+        UpdatePSBTOutput(HidingSigningProvider(pwallet, true, !bip32derivs),
+                         psbtx, i);
     }
 
     return TransactionError::OK;