diff --git a/src/wallet/bdb.cpp b/src/wallet/bdb.cpp
index 658500e4563..9ea43ca67c5 100644
--- a/src/wallet/bdb.cpp
+++ b/src/wallet/bdb.cpp
@@ -18,6 +18,7 @@
 
 #include <stdint.h>
 
+#include <db_cxx.h>
 #include <sys/stat.h>
 
 // Windows may not define S_IRUSR or S_IWUSR. We define both
@@ -29,12 +30,10 @@
 #endif
 #endif
 
+static_assert(BDB_DB_FILE_ID_LEN == DB_FILE_ID_LEN, "DB_FILE_ID_LEN should be 20.");
+
 namespace wallet {
 namespace {
-Span<const std::byte> SpanFromDbt(const SafeDbt& dbt)
-{
-    return {reinterpret_cast<const std::byte*>(dbt.get_data()), dbt.get_size()};
-}
 
 //! Make sure database has a unique fileid within the environment. If it
 //! doesn't, throw an error. BDB caches do not work properly when more than one
@@ -236,6 +235,26 @@ BerkeleyEnvironment::BerkeleyEnvironment() : m_use_shared_memory(false)
     fMockDb = true;
 }
 
+/** RAII class that automatically cleanses its data on destruction */
+class SafeDbt final
+{
+    Dbt m_dbt;
+
+public:
+    // construct Dbt with internally-managed data
+    SafeDbt();
+    // construct Dbt with provided data
+    SafeDbt(void* data, size_t size);
+    ~SafeDbt();
+
+    // delegate to Dbt
+    const void* get_data() const;
+    uint32_t get_size() const;
+
+    // conversion operator to access the underlying Dbt
+    operator Dbt*();
+};
+
 SafeDbt::SafeDbt()
 {
     m_dbt.set_flags(DB_DBT_MALLOC);
@@ -275,6 +294,18 @@ SafeDbt::operator Dbt*()
     return &m_dbt;
 }
 
+static Span<const std::byte> SpanFromDbt(const SafeDbt& dbt)
+{
+    return {reinterpret_cast<const std::byte*>(dbt.get_data()), dbt.get_size()};
+}
+
+BerkeleyDatabase::BerkeleyDatabase(std::shared_ptr<BerkeleyEnvironment> env, fs::path filename, const DatabaseOptions& options) :
+    WalletDatabase(), env(std::move(env)), m_filename(std::move(filename)), m_max_log_mb(options.max_log_mb)
+{
+    auto inserted = this->env->m_databases.emplace(m_filename, std::ref(*this));
+    assert(inserted.second);
+}
+
 bool BerkeleyDatabase::Verify(bilingual_str& errorStr)
 {
     fs::path walletDir = env->Directory();
@@ -462,6 +493,15 @@ void BerkeleyEnvironment::ReloadDbEnv()
     Open(open_err);
 }
 
+DbTxn* BerkeleyEnvironment::TxnBegin(int flags)
+{
+    DbTxn* ptxn = nullptr;
+    int ret = dbenv->txn_begin(nullptr, &ptxn, flags);
+    if (!ptxn || ret != 0)
+        return nullptr;
+    return ptxn;
+}
+
 bool BerkeleyDatabase::Rewrite(const char* pszSkip)
 {
     while (true) {
@@ -742,7 +782,7 @@ bool BerkeleyBatch::TxnBegin()
 {
     if (!pdb || activeTxn)
         return false;
-    DbTxn* ptxn = env->TxnBegin();
+    DbTxn* ptxn = env->TxnBegin(DB_TXN_WRITE_NOSYNC);
     if (!ptxn)
         return false;
     activeTxn = ptxn;
diff --git a/src/wallet/bdb.h b/src/wallet/bdb.h
index 1073d32e0f2..630630ebe01 100644
--- a/src/wallet/bdb.h
+++ b/src/wallet/bdb.h
@@ -21,14 +21,21 @@
 #include <unordered_map>
 #include <vector>
 
-#include <db_cxx.h>
-
 struct bilingual_str;
 
+class DbEnv;
+class DbTxn;
+class Db;
+class Dbc;
+
+// This constant was introduced in BDB 4.0.14 and has never changed, but there
+// is a belt-and-suspenders check in the cpp file just in case.
+#define BDB_DB_FILE_ID_LEN 20 /* Unique file ID length. */
+
 namespace wallet {
 
 struct WalletDatabaseFileId {
-    uint8_t value[DB_FILE_ID_LEN];
+    uint8_t value[BDB_DB_FILE_ID_LEN];
     bool operator==(const WalletDatabaseFileId& rhs) const;
 };
 
@@ -67,14 +74,7 @@ public:
     void CloseDb(const fs::path& filename);
     void ReloadDbEnv();
 
-    DbTxn* TxnBegin(int flags = DB_TXN_WRITE_NOSYNC)
-    {
-        DbTxn* ptxn = nullptr;
-        int ret = dbenv->txn_begin(nullptr, &ptxn, flags);
-        if (!ptxn || ret != 0)
-            return nullptr;
-        return ptxn;
-    }
+    DbTxn* TxnBegin(int flags);
 };
 
 /** Get BerkeleyEnvironment given a directory path. */
@@ -91,12 +91,7 @@ public:
     BerkeleyDatabase() = delete;
 
     /** Create DB handle to real database */
-    BerkeleyDatabase(std::shared_ptr<BerkeleyEnvironment> env, fs::path filename, const DatabaseOptions& options) :
-        WalletDatabase(), env(std::move(env)), m_filename(std::move(filename)), m_max_log_mb(options.max_log_mb)
-    {
-        auto inserted = this->env->m_databases.emplace(m_filename, std::ref(*this));
-        assert(inserted.second);
-    }
+    BerkeleyDatabase(std::shared_ptr<BerkeleyEnvironment> env, fs::path filename, const DatabaseOptions& options);
 
     ~BerkeleyDatabase() override;
 
@@ -159,26 +154,6 @@ public:
     std::unique_ptr<DatabaseBatch> MakeBatch(bool flush_on_close = true) override;
 };
 
-/** RAII class that automatically cleanses its data on destruction */
-class SafeDbt final
-{
-    Dbt m_dbt;
-
-public:
-    // construct Dbt with internally-managed data
-    SafeDbt();
-    // construct Dbt with provided data
-    SafeDbt(void* data, size_t size);
-    ~SafeDbt();
-
-    // delegate to Dbt
-    const void* get_data() const;
-    uint32_t get_size() const;
-
-    // conversion operator to access the underlying Dbt
-    operator Dbt*();
-};
-
 class BerkeleyCursor : public DatabaseCursor
 {
 private:
diff --git a/src/wallet/salvage.cpp b/src/wallet/salvage.cpp
index da16435f041..0a0745b1c50 100644
--- a/src/wallet/salvage.cpp
+++ b/src/wallet/salvage.cpp
@@ -11,6 +11,8 @@
 #include <wallet/wallet.h>
 #include <wallet/walletdb.h>
 
+#include <db_cxx.h>
+
 namespace wallet {
 /* End of headers, beginning of key/value data */
 static const char *HEADER_END = "HEADER=END";
@@ -175,7 +177,7 @@ bool RecoverDatabaseFile(const ArgsManager& args, const fs::path& file_path, bil
         return false;
     }
 
-    DbTxn* ptxn = env->TxnBegin();
+    DbTxn* ptxn = env->TxnBegin(DB_TXN_WRITE_NOSYNC);
     CWallet dummyWallet(nullptr, "", std::make_unique<DummyDatabase>());
     for (KeyValPair& row : salvagedData)
     {