diff --git a/src/httpserver.cpp b/src/httpserver.cpp
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -39,7 +39,7 @@
 static const size_t MAX_HEADERS_SIZE = 8192;
 
 /** HTTP request work item */
-class HTTPWorkItem : public HTTPClosure {
+class HTTPWorkItem final : public HTTPClosure {
 public:
     HTTPWorkItem(Config &_config, std::unique_ptr<HTTPRequest> _req,
                  const std::string &_path, const HTTPRequestHandler &_func)
@@ -591,10 +591,10 @@
     struct evbuffer *evb = evhttp_request_get_output_buffer(req);
     assert(evb);
     evbuffer_add(evb, strReply.data(), strReply.size());
-    HTTPEvent *ev =
-        new HTTPEvent(eventBase, true, std::bind(evhttp_send_reply, req,
-                                                 nStatus, (const char *)nullptr,
-                                                 (struct evbuffer *)nullptr));
+    HTTPEvent *ev = new HTTPEvent(eventBase, true,
+                                  std::bind(evhttp_send_reply, req, nStatus,
+                                            (const char *)nullptr,
+                                            (struct evbuffer *)nullptr));
     ev->trigger(0);
     replySent = true;
     // transferred back to main thread.
diff --git a/src/init.cpp b/src/init.cpp
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -139,7 +139,7 @@
  * the chainstate, while keeping user interface out of the common library, which
  * is shared between bitcoind, and bitcoin-qt and non-server tools.
  */
-class CCoinsViewErrorCatcher : public CCoinsViewBacked {
+class CCoinsViewErrorCatcher final : public CCoinsViewBacked {
 public:
     CCoinsViewErrorCatcher(CCoinsView *view) : CCoinsViewBacked(view) {}
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override {
@@ -460,9 +460,8 @@
                                _("Discover own IP addresses (default: 1 when "
                                  "listening and no -externalip or -proxy)"));
     strUsage += HelpMessageOpt(
-        "-dns",
-        _("Allow DNS lookups for -addnode, -seednode and -connect") + " " +
-            strprintf(_("(default: %d)"), DEFAULT_NAME_LOOKUP));
+        "-dns", _("Allow DNS lookups for -addnode, -seednode and -connect") +
+                    " " + strprintf(_("(default: %d)"), DEFAULT_NAME_LOOKUP));
     strUsage += HelpMessageOpt(
         "-dnsseed", _("Query for peer addresses via DNS lookup, if low on "
                       "addresses (default: 1 unless -connect/-noconnect)"));
@@ -562,9 +561,10 @@
         _("Whitelist peers connecting from the given IP address (e.g. 1.2.3.4) "
           "or CIDR notated network (e.g. 1.2.3.0/24). Can be specified "
           "multiple times.") +
-            " " + _("Whitelisted peers cannot be DoS banned and their "
-                    "transactions are always relayed, even if they are already "
-                    "in the mempool, useful e.g. for a gateway"));
+            " " +
+            _("Whitelisted peers cannot be DoS banned and their "
+              "transactions are always relayed, even if they are already "
+              "in the mempool, useful e.g. for a gateway"));
     strUsage += HelpMessageOpt(
         "-whitelistrelay",
         strprintf(_("Accept relayed transactions received from whitelisted "
@@ -682,8 +682,9 @@
         strprintf(_("Output debugging information (default: %u, supplying "
                     "<category> is optional)"),
                   0) +
-            ". " + _("If <category> is not supplied or if <category> = 1, "
-                     "output all debugging information.") +
+            ". " +
+            _("If <category> is not supplied or if <category> = 1, "
+              "output all debugging information.") +
             _("<category> can be:") + " " + ListLogCategories() + ".");
     strUsage += HelpMessageOpt(
         "-debugexclude=<category>",
@@ -895,8 +896,9 @@
            strprintf(_("Please contribute if you find %s useful. "
                        "Visit %s for further information about the software."),
                      PACKAGE_NAME, URL_WEBSITE) +
-           "\n" + strprintf(_("The source code is available from %s."),
-                            URL_SOURCE_CODE) +
+           "\n" +
+           strprintf(_("The source code is available from %s."),
+                     URL_SOURCE_CODE) +
            "\n" + "\n" + _("This is experimental software.") + "\n" +
            strprintf(_("Distributed under the MIT software license, see the "
                        "accompanying file %s or %s"),
@@ -1924,11 +1926,11 @@
     // total cache cannot be greater than nMaxDbcache
     nTotalCache = std::min(nTotalCache, nMaxDbCache << 20);
     int64_t nBlockTreeDBCache = nTotalCache / 8;
-    nBlockTreeDBCache = std::min(nBlockTreeDBCache,
-                                 (GetBoolArg("-txindex", DEFAULT_TXINDEX)
-                                      ? nMaxBlockDBAndTxIndexCache
-                                      : nMaxBlockDBCache)
-                                     << 20);
+    nBlockTreeDBCache =
+        std::min(nBlockTreeDBCache, (GetBoolArg("-txindex", DEFAULT_TXINDEX)
+                                         ? nMaxBlockDBAndTxIndexCache
+                                         : nMaxBlockDBCache)
+                                        << 20);
     nTotalCache -= nBlockTreeDBCache;
     // use 25%-50% of the remainder for disk cache
     int64_t nCoinDBCache =
@@ -2036,9 +2038,8 @@
                 }
 
                 uiInterface.InitMessage(_("Verifying blocks..."));
-                if (fHavePruned &&
-                    GetArg("-checkblocks", DEFAULT_CHECKBLOCKS) >
-                        MIN_BLOCKS_TO_KEEP) {
+                if (fHavePruned && GetArg("-checkblocks", DEFAULT_CHECKBLOCKS) >
+                                       MIN_BLOCKS_TO_KEEP) {
                     LogPrintf("Prune: pruned datadir may not have more than %d "
                               "blocks; only checking available blocks",
                               MIN_BLOCKS_TO_KEEP);
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -583,7 +583,7 @@
  * transactions and balances, and provides the ability to create new
  * transactions.
  */
-class CWallet : public CCryptoKeyStore, public CValidationInterface {
+class CWallet final : public CCryptoKeyStore, public CValidationInterface {
 private:
     static std::atomic<bool> fFlushScheduled;
 
@@ -1127,7 +1127,7 @@
 };
 
 /** A key allocated from the key pool. */
-class CReserveKey : public CReserveScript {
+class CReserveKey final : public CReserveScript {
 protected:
     CWallet *pwallet;
     int64_t nIndex;
diff --git a/src/zmq/zmqnotificationinterface.h b/src/zmq/zmqnotificationinterface.h
--- a/src/zmq/zmqnotificationinterface.h
+++ b/src/zmq/zmqnotificationinterface.h
@@ -13,7 +13,7 @@
 class CBlockIndex;
 class CZMQAbstractNotifier;
 
-class CZMQNotificationInterface : public CValidationInterface {
+class CZMQNotificationInterface final : public CValidationInterface {
 public:
     virtual ~CZMQNotificationInterface();