diff --git a/src/script/sign.h b/src/script/sign.h
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -38,6 +38,17 @@
 
 extern const SigningProvider &DUMMY_SIGNING_PROVIDER;
 
+class PublicOnlySigningProvider : public SigningProvider {
+private:
+    const SigningProvider *m_provider;
+
+public:
+    PublicOnlySigningProvider(const SigningProvider *provider)
+        : m_provider(provider) {}
+    bool GetCScript(const CScriptID &scriptid, CScript &script) const;
+    bool GetPubKey(const CKeyID &address, CPubKey &pubkey) const;
+};
+
 /** Interface for signature creators. */
 class BaseSignatureCreator {
 public:
@@ -210,8 +221,10 @@
 
     template <typename Stream> inline void Serialize(Stream &s) const {
         // Write the utxo
-        SerializeToVector(s, PSBT_IN_UTXO);
-        SerializeToVector(s, utxo);
+        if (!utxo.IsNull()) {
+            SerializeToVector(s, PSBT_IN_UTXO);
+            SerializeToVector(s, utxo);
+        }
 
         if (final_script_sig.empty()) {
             // Write any partial signatures
@@ -493,6 +506,7 @@
         for (const PSBTInput &input : inputs) {
             s << input;
         }
+
         // Write outputs
         for (const PSBTOutput &output : outputs) {
             s << output;
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -220,7 +220,7 @@
 bool SignPSBTInput(const SigningProvider &provider,
                    const CMutableTransaction &tx, PSBTInput &input,
                    SignatureData &sigdata, int index, SigHashType sighash) {
-    // if this input has a final scriptsig, don't do anything with it
+    // If this input has a final scriptsig, don't do anything with it.
     if (!input.final_script_sig.empty()) {
         return true;
     }
@@ -544,3 +544,13 @@
         redeem_script = output.redeem_script;
     }
 }
+
+bool PublicOnlySigningProvider::GetCScript(const CScriptID &scriptid,
+                                           CScript &script) const {
+    return m_provider->GetCScript(scriptid, script);
+}
+
+bool PublicOnlySigningProvider::GetPubKey(const CKeyID &address,
+                                          CPubKey &pubkey) const {
+    return m_provider->GetPubKey(address, pubkey);
+}