diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index e6fc1feb2b0..0b7cd4a4dc1 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -211,8 +211,8 @@ public:
      */
     virtual bool ToNormalizedString(const SigningProvider& arg, std::string& out, const DescriptorCache* cache = nullptr) const = 0;
 
-    /** Derive a private key, if private data is available in arg. */
-    virtual bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const = 0;
+    /** Derive a private key, if private data is available in arg and put it into out. */
+    virtual void GetPrivKey(int pos, const SigningProvider& arg, FlatSigningProvider& out) const = 0;
 
     /** Return the non-extended public key for this PubkeyProvider, if it has one. */
     virtual std::optional<CPubKey> GetRootPubKey() const = 0;
@@ -274,9 +274,9 @@ public:
         }
         return true;
     }
-    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
+    void GetPrivKey(int pos, const SigningProvider& arg, FlatSigningProvider& out) const override
     {
-        return m_provider->GetPrivKey(pos, arg, key);
+        m_provider->GetPrivKey(pos, arg, out);
     }
     std::optional<CPubKey> GetRootPubKey() const override
     {
@@ -298,6 +298,14 @@ class ConstPubkeyProvider final : public PubkeyProvider
     CPubKey m_pubkey;
     bool m_xonly;
 
+    std::optional<CKey> GetPrivKey(const SigningProvider& arg) const
+    {
+        CKey key;
+        if (!(m_xonly ? arg.GetKeyByXOnly(XOnlyPubKey(m_pubkey), key) :
+                        arg.GetKey(m_pubkey.GetID(), key))) return std::nullopt;
+        return key;
+    }
+
 public:
     ConstPubkeyProvider(uint32_t exp_index, const CPubKey& pubkey, bool xonly) : PubkeyProvider(exp_index), m_pubkey(pubkey), m_xonly(xonly) {}
     std::optional<CPubKey> GetPubKey(int pos, const SigningProvider&, FlatSigningProvider& out, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) const override
@@ -314,9 +322,9 @@ public:
     std::string ToString(StringType type) const override { return m_xonly ? HexStr(m_pubkey).substr(2) : HexStr(m_pubkey); }
     bool ToPrivateString(const SigningProvider& arg, std::string& ret) const override
     {
-        CKey key;
-        if (!GetPrivKey(/*pos=*/0, arg, key)) return false;
-        ret = EncodeSecret(key);
+        std::optional<CKey> key = GetPrivKey(arg);
+        if (!key) return false;
+        ret = EncodeSecret(*key);
         return true;
     }
     bool ToNormalizedString(const SigningProvider& arg, std::string& ret, const DescriptorCache* cache) const override
@@ -324,10 +332,11 @@ public:
         ret = ToString(StringType::PUBLIC);
         return true;
     }
-    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
+    void GetPrivKey(int pos, const SigningProvider& arg, FlatSigningProvider& out) const override
     {
-        return m_xonly ? arg.GetKeyByXOnly(XOnlyPubKey(m_pubkey), key) :
-                         arg.GetKey(m_pubkey.GetID(), key);
+        std::optional<CKey> key = GetPrivKey(arg);
+        if (!key) return;
+        out.keys.emplace(key->GetPubKey().GetID(), *key);
     }
     std::optional<CPubKey> GetRootPubKey() const override
     {
@@ -542,15 +551,14 @@ public:
         }
         return true;
     }
-    bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
+    void GetPrivKey(int pos, const SigningProvider& arg, FlatSigningProvider& out) const override
     {
         CExtKey extkey;
         CExtKey dummy;
-        if (!GetDerivedExtKey(arg, extkey, dummy)) return false;
-        if (m_derive == DeriveType::UNHARDENED && !extkey.Derive(extkey, pos)) return false;
-        if (m_derive == DeriveType::HARDENED && !extkey.Derive(extkey, pos | 0x80000000UL)) return false;
-        key = extkey.key;
-        return true;
+        if (!GetDerivedExtKey(arg, extkey, dummy)) return;
+        if (m_derive == DeriveType::UNHARDENED && !extkey.Derive(extkey, pos)) return;
+        if (m_derive == DeriveType::HARDENED && !extkey.Derive(extkey, pos | 0x80000000UL)) return;
+        out.keys.emplace(extkey.key.GetPubKey().GetID(), extkey.key);
     }
     std::optional<CPubKey> GetRootPubKey() const override
     {
@@ -736,9 +744,7 @@ public:
     void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const final
     {
         for (const auto& p : m_pubkey_args) {
-            CKey key;
-            if (!p->GetPrivKey(pos, provider, key)) continue;
-            out.keys.emplace(key.GetPubKey().GetID(), key);
+            p->GetPrivKey(pos, provider, out);
         }
         for (const auto& arg : m_subdescriptor_args) {
             arg->ExpandPrivate(pos, provider, out);