diff --git a/src/interfaces/wallet.h b/src/interfaces/wallet.h
--- a/src/interfaces/wallet.h
+++ b/src/interfaces/wallet.h
@@ -191,7 +191,7 @@
     virtual TransactionError fillPSBT(SigHashType sighash_type, bool sign,
                                       bool bip32derivs,
                                       PartiallySignedTransaction &psbtx,
-                                      bool &complete) = 0;
+                                      bool &complete) const = 0;
 
     //! Get balances.
     virtual WalletBalances getBalances() = 0;
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -20,7 +20,6 @@
 #include <wallet/fees.h>
 #include <wallet/ismine.h>
 #include <wallet/load.h>
-#include <wallet/psbtwallet.h>
 #include <wallet/rpcdump.h>
 #include <wallet/wallet.h>
 
@@ -313,9 +312,9 @@
         TransactionError fillPSBT(SigHashType sighash_type, bool sign,
                                   bool bip32derivs,
                                   PartiallySignedTransaction &psbtx,
-                                  bool &complete) override {
-            return FillPSBT(m_wallet.get(), psbtx, complete, sighash_type, sign,
-                            bip32derivs);
+                                  bool &complete) const override {
+            return m_wallet->FillPSBT(psbtx, complete, sighash_type, sign,
+                                      bip32derivs);
         }
         WalletBalances getBalances() override {
             const auto bal = m_wallet->GetBalance();
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -24,7 +24,6 @@
 #include <ui_interface.h>
 #include <wallet/coincontrol.h>
 #include <wallet/fees.h>
-#include <wallet/psbtwallet.h>
 #include <wallet/wallet.h>
 
 #include <QScrollBar>
diff --git a/src/wallet/CMakeLists.txt b/src/wallet/CMakeLists.txt
--- a/src/wallet/CMakeLists.txt
+++ b/src/wallet/CMakeLists.txt
@@ -18,7 +18,6 @@
 	db.cpp
 	fees.cpp
 	load.cpp
-	psbtwallet.cpp
 	rpcdump.cpp
 	rpcwallet.cpp
 	scriptpubkeyman.cpp
diff --git a/src/wallet/psbtwallet.h b/src/wallet/psbtwallet.h
deleted file mode 100644
--- a/src/wallet/psbtwallet.h
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright (c) 2009-2019 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#ifndef BITCOIN_WALLET_PSBTWALLET_H
-#define BITCOIN_WALLET_PSBTWALLET_H
-
-#include <psbt.h>
-#include <wallet/wallet.h>
-
-/**
- * Fills out a PSBT with information from the wallet. Fills in UTXOs if we have
- * them. Tries to sign if sign=true. Sets `complete` if the PSBT is now complete
- * (i.e. has all required signatures or signature-parts, and is ready to
- * finalize.) Sets `error` and returns false if something goes wrong.
- *
- * @param[in]  pwallet pointer to a wallet
- * @param[in]  &psbtx reference to PartiallySignedTransaction to fill in
- * @param[out] &complete indicates whether the PSBT is now complete
- * @param[in]  sighash_type the sighash type to use when signing (if PSBT does
- * not specify)
- * @param[in]  sign whether to sign or not
- * @param[in] bip32derivs whether to fill in bip32 derivation information if
- * available
- * @return error
- */
-NODISCARD TransactionError
-FillPSBT(const CWallet *pwallet, PartiallySignedTransaction &psbtx,
-         bool &complete, SigHashType sighash_type = SigHashType().withForkId(),
-         bool sign = true, bool bip32derivs = true);
-
-#endif // BITCOIN_WALLET_PSBTWALLET_H
diff --git a/src/wallet/psbtwallet.cpp b/src/wallet/psbtwallet.cpp
deleted file mode 100644
--- a/src/wallet/psbtwallet.cpp
+++ /dev/null
@@ -1,83 +0,0 @@
-// Copyright (c) 2009-2018 The Bitcoin Core developers
-// Distributed under the MIT software license, see the accompanying
-// file COPYING or http://www.opensource.org/licenses/mit-license.php.
-
-#include <util/error.h>
-#include <wallet/psbtwallet.h>
-
-TransactionError FillPSBT(const CWallet *pwallet,
-                          PartiallySignedTransaction &psbtx, bool &complete,
-                          SigHashType sighash_type, bool sign,
-                          bool bip32derivs) {
-    LOCK(pwallet->cs_wallet);
-    // Get all of the previous transactions
-    complete = true;
-    for (size_t i = 0; i < psbtx.tx->vin.size(); ++i) {
-        const CTxIn &txin = psbtx.tx->vin[i];
-        PSBTInput &input = psbtx.inputs.at(i);
-
-        if (PSBTInputSigned(input)) {
-            continue;
-        }
-
-        // Verify input looks sane.
-        if (!input.IsSane()) {
-            return TransactionError::INVALID_PSBT;
-        }
-
-        // If we have no utxo, grab it from the wallet.
-        if (input.utxo.IsNull()) {
-            const TxId &txid = txin.prevout.GetTxId();
-            const auto it = pwallet->mapWallet.find(txid);
-            if (it != pwallet->mapWallet.end()) {
-                const CWalletTx &wtx = it->second;
-                CTxOut utxo = wtx.tx->vout[txin.prevout.GetN()];
-                // Update UTXOs from the wallet.
-                input.utxo = utxo;
-            }
-        }
-
-        // Get the Sighash type
-        if (sign && input.sighash_type.getRawSigHashType() > 0 &&
-            input.sighash_type != sighash_type) {
-            return TransactionError::SIGHASH_MISMATCH;
-        }
-
-        // Get the scriptPubKey to know which SigningProvider to use
-        CScript script;
-        if (!input.utxo.IsNull()) {
-            script = input.utxo.scriptPubKey;
-        } else {
-            // There's no UTXO so we can just skip this now
-            complete = false;
-            continue;
-        }
-        SignatureData sigdata;
-        input.FillSignatureData(sigdata);
-        std::unique_ptr<SigningProvider> provider =
-            pwallet->GetSigningProvider(script, sigdata);
-        if (!provider) {
-            complete = false;
-            continue;
-        }
-
-        complete &= SignPSBTInput(
-            HidingSigningProvider(provider.get(), !sign, !bip32derivs), psbtx,
-            i, sighash_type);
-    }
-
-    // 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);
-        std::unique_ptr<SigningProvider> provider =
-            pwallet->GetSigningProvider(out.scriptPubKey);
-        if (provider) {
-            UpdatePSBTOutput(
-                HidingSigningProvider(provider.get(), true, !bip32derivs),
-                psbtx, i);
-        }
-    }
-
-    return TransactionError::OK;
-}
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -27,7 +27,6 @@
 #include <util/translation.h>
 #include <util/url.h>
 #include <wallet/coincontrol.h>
-#include <wallet/psbtwallet.h>
 #include <wallet/rpcwallet.h>
 #include <wallet/wallet.h>
 #include <wallet/walletdb.h>
@@ -4575,7 +4574,7 @@
         request.params[3].isNull() ? true : request.params[3].get_bool();
     bool complete = true;
     const TransactionError err =
-        FillPSBT(pwallet, psbtx, complete, nHashType, sign, bip32derivs);
+        pwallet->FillPSBT(psbtx, complete, nHashType, sign, bip32derivs);
     if (err != TransactionError::OK) {
         throw JSONRPCTransactionError(err);
     }
@@ -4751,9 +4750,8 @@
     bool bip32derivs =
         request.params[4].isNull() ? true : request.params[4].get_bool();
     bool complete = true;
-    const TransactionError err =
-        FillPSBT(pwallet, psbtx, complete, SigHashType().withForkId(), false,
-                 bip32derivs);
+    const TransactionError err = pwallet->FillPSBT(
+        psbtx, complete, SigHashType().withForkId(), false, bip32derivs);
     if (err != TransactionError::OK) {
         throw JSONRPCTransactionError(err);
     }
diff --git a/src/wallet/test/psbt_wallet_tests.cpp b/src/wallet/test/psbt_wallet_tests.cpp
--- a/src/wallet/test/psbt_wallet_tests.cpp
+++ b/src/wallet/test/psbt_wallet_tests.cpp
@@ -6,7 +6,6 @@
 #include <util/bip32.h>
 #include <util/error.h>
 #include <util/strencodings.h>
-#include <wallet/psbtwallet.h>
 #include <wallet/test/wallet_test_fixture.h>
 #include <wallet/wallet.h>
 
@@ -94,7 +93,7 @@
     // Fill transaction with our data
     bool complete = true;
     BOOST_REQUIRE_EQUAL(
-        FillPSBT(&m_wallet, psbtx, complete, SigHashType(), false, true),
+        m_wallet.FillPSBT(psbtx, complete, SigHashType(), false, true),
         TransactionError::OK);
 
     // Get the final tx
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -12,6 +12,7 @@
 #include <interfaces/handler.h>
 #include <outputtype.h>
 #include <primitives/blockhash.h>
+#include <psbt.h>
 #include <tinyformat.h>
 #include <ui_interface.h>
 #include <util/strencodings.h>
@@ -1106,6 +1107,26 @@
                          SigHashType sighash,
                          std::map<int, std::string> &input_errors) const;
 
+    /**
+     * Fills out a PSBT with information from the wallet. Fills in UTXOs if we
+     * have them. Tries to sign if sign=true. Sets `complete` if the PSBT is now
+     * complete (i.e. has all required signatures or signature-parts, and is
+     * ready to finalize.) Sets `error` and returns false if something goes
+     * wrong.
+     *
+     * @param[in]  psbtx PartiallySignedTransaction to fill in
+     * @param[out] complete indicates whether the PSBT is now complete
+     * @param[in]  sighash_type the sighash type to use when signing (if PSBT
+     * does not specify)
+     * @param[in]  sign whether to sign or not
+     * @param[in]  bip32derivs whether to fill in bip32 derivation information
+     * if available return error
+     */
+    TransactionError
+    FillPSBT(PartiallySignedTransaction &psbtx, bool &complete,
+             SigHashType sighash_type = SigHashType().withForkId(),
+             bool sign = true, bool bip32derivs = true) const;
+
     /**
      * Create a new transaction paying the recipients with a set of coins
      * selected by SelectCoins(); Also create the change output, when needed
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2791,6 +2791,82 @@
     return false;
 }
 
+TransactionError CWallet::FillPSBT(PartiallySignedTransaction &psbtx,
+                                   bool &complete, SigHashType sighash_type,
+                                   bool sign, bool bip32derivs) const {
+    LOCK(cs_wallet);
+    // Get all of the previous transactions
+    complete = true;
+    for (size_t i = 0; i < psbtx.tx->vin.size(); ++i) {
+        const CTxIn &txin = psbtx.tx->vin[i];
+        PSBTInput &input = psbtx.inputs.at(i);
+
+        if (PSBTInputSigned(input)) {
+            continue;
+        }
+
+        // Verify input looks sane.
+        if (!input.IsSane()) {
+            return TransactionError::INVALID_PSBT;
+        }
+
+        // If we have no utxo, grab it from the wallet.
+        if (input.utxo.IsNull()) {
+            const TxId &txid = txin.prevout.GetTxId();
+            const auto it = mapWallet.find(txid);
+            if (it != mapWallet.end()) {
+                const CWalletTx &wtx = it->second;
+                CTxOut utxo = wtx.tx->vout[txin.prevout.GetN()];
+                // Update UTXOs from the wallet.
+                input.utxo = utxo;
+            }
+        }
+
+        // Get the Sighash type
+        if (sign && input.sighash_type.getRawSigHashType() > 0 &&
+            input.sighash_type != sighash_type) {
+            return TransactionError::SIGHASH_MISMATCH;
+        }
+
+        // Get the scriptPubKey to know which SigningProvider to use
+        CScript script;
+        if (!input.utxo.IsNull()) {
+            script = input.utxo.scriptPubKey;
+        } else {
+            // There's no UTXO so we can just skip this now
+            complete = false;
+            continue;
+        }
+        SignatureData sigdata;
+        input.FillSignatureData(sigdata);
+        std::unique_ptr<SigningProvider> provider =
+            GetSigningProvider(script, sigdata);
+        if (!provider) {
+            complete = false;
+            continue;
+        }
+
+        complete &= SignPSBTInput(
+            HidingSigningProvider(provider.get(), !sign, !bip32derivs), psbtx,
+            i, sighash_type);
+    }
+
+    // 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);
+        std::unique_ptr<SigningProvider> provider =
+            GetSigningProvider(out.scriptPubKey);
+        if (provider) {
+            UpdatePSBTOutput(
+                HidingSigningProvider(provider.get(), true, !bip32derivs),
+                psbtx, i);
+        }
+    }
+
+    return TransactionError::OK;
+}
+
 bool CWallet::FundTransaction(CMutableTransaction &tx, Amount &nFeeRet,
                               int &nChangePosInOut, bilingual_str &error,
                               bool lockUnspents,