diff --git a/daemon/daemon.cc b/daemon/daemon.cc
index bdd4e5833..c73a6096a 100644
--- a/daemon/daemon.cc
+++ b/daemon/daemon.cc
@@ -51,6 +51,7 @@ static void sd_notifyf(int /*status*/, char const* /*fmt*/, ...)
 
 #endif
 
+using namespace std::literals;
 using libtransmission::Watchdir;
 
 static char constexpr MyName[] = "transmission-daemon";
@@ -199,7 +200,7 @@ static std::string getConfigDir(int argc, char const* const* argv)
     return tr_getDefaultConfigDir(MyName);
 }
 
-static auto onFileAdded(tr_session* session, std::string_view dirname, std::string_view basename)
+static auto onFileAdded(tr_session const* session, std::string_view dirname, std::string_view basename)
 {
     auto const lowercase = tr_strlower(basename);
     auto const is_torrent = tr_strvEndsWith(lowercase, ".torrent"sv);
@@ -921,7 +922,7 @@ EXIT_EARLY:
     return false;
 }
 
-void tr_daemon::handle_error(tr_error* error)
+void tr_daemon::handle_error(tr_error* error) const
 {
     auto const errmsg = fmt::format(FMT_STRING("Couldn't daemonize: {:s} ({:d})"), error->message, error->code);
     printMessage(logfile_, TR_LOG_ERROR, MyName, errmsg, __FILE__, __LINE__);
diff --git a/daemon/daemon.h b/daemon/daemon.h
index 375535910..49291f456 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -15,8 +15,6 @@
 #include <libtransmission/file.h>
 #include <libtransmission/log.h>
 
-using namespace std::literals;
-
 class tr_daemon
 {
 public:
@@ -35,7 +33,7 @@ public:
 
     bool spawn(bool foreground, int* exit_code, tr_error** error);
     bool init(int argc, char* argv[], bool* foreground, int* ret);
-    void handle_error(tr_error*);
+    void handle_error(tr_error*) const;
     int start(bool foreground);
     void periodic_update();
     void reconfigure();
@@ -53,8 +51,8 @@ private:
     char const* log_file_name_ = nullptr;
     struct event_base* ev_base_ = nullptr;
     tr_sys_file_t logfile_ = TR_BAD_SYS_FILE;
-    tr_quark key_pidfile_ = tr_quark_new("pidfile"sv);
-    tr_quark key_watch_dir_force_generic_ = tr_quark_new("watch-dir-force-generic"sv);
+    tr_quark key_pidfile_ = tr_quark_new("pidfile");
+    tr_quark key_watch_dir_force_generic_ = tr_quark_new("watch-dir-force-generic");
 
     bool parse_args(int argc, char const** argv, bool* dump_settings, bool* foreground, int* exit_code);
     bool reopen_log_file(char const* filename);
diff --git a/qt/Application.h b/qt/Application.h
index e0d475027..5e052769f 100644
--- a/qt/Application.h
+++ b/qt/Application.h
@@ -21,13 +21,12 @@
 #include "Utils.h" // std::hash<QString>
 
 class AddData;
+class MainWindow;
 class Prefs;
 class Session;
 class Torrent;
 class TorrentModel;
-class MainWindow;
 class WatchDir;
-class Torrent;
 
 class Application : public QApplication
 {
diff --git a/qt/FileTreeView.cc b/qt/FileTreeView.cc
index 082b0b1f1..a41cd8299 100644
--- a/qt/FileTreeView.cc
+++ b/qt/FileTreeView.cc
@@ -156,9 +156,8 @@ void FileTreeView::keyPressEvent(QKeyEvent* event)
 
 void FileTreeView::mouseDoubleClickEvent(QMouseEvent* event)
 {
-    auto const index = currentIndex();
-
-    if (!index.isValid() || index.column() == FileTreeModel::COL_WANTED || index.column() == FileTreeModel::COL_PRIORITY)
+    if (auto const index = currentIndex();
+        !index.isValid() || index.column() == FileTreeModel::COL_WANTED || index.column() == FileTreeModel::COL_PRIORITY)
     {
         return;
     }
@@ -173,9 +172,7 @@ void FileTreeView::mouseDoubleClickEvent(QMouseEvent* event)
 
 void FileTreeView::contextMenuEvent(QContextMenuEvent* event)
 {
-    QModelIndex const root_index = model_->index(0, 0);
-
-    if (!root_index.isValid())
+    if (auto const root_index = model_->index(0, 0); !root_index.isValid())
     {
         return;
     }
diff --git a/qt/IconCache.cc b/qt/IconCache.cc
index c7fe695bb..471db1494 100644
--- a/qt/IconCache.cc
+++ b/qt/IconCache.cc
@@ -224,7 +224,7 @@ QIcon IconCache::getThemeIcon(
     QString const& fallbackName,
     std::optional<QStyle::StandardPixmap> const& fallbackPixmap) const
 {
-    auto const rtl_suffix = qApp->layoutDirection() == Qt::RightToLeft ? QStringLiteral("-rtl") : QString();
+    auto const rtl_suffix = QApplication::layoutDirection() == Qt::RightToLeft ? QStringLiteral("-rtl") : QString();
 
     auto icon = QIcon::fromTheme(name + rtl_suffix);
 
@@ -235,7 +235,7 @@ QIcon IconCache::getThemeIcon(
 
     if (icon.isNull() && fallbackPixmap.has_value())
     {
-        icon = qApp->style()->standardIcon(*fallbackPixmap, nullptr);
+        icon = QApplication::style()->standardIcon(*fallbackPixmap, nullptr);
     }
 
     return icon;
diff --git a/qt/RpcClient.cc b/qt/RpcClient.cc
index 9de81b160..ab70a4a5b 100644
--- a/qt/RpcClient.cc
+++ b/qt/RpcClient.cc
@@ -285,8 +285,7 @@ void RpcClient::localRequestFinished(TrVariantPtr response)
 
 int64_t RpcClient::parseResponseTag(tr_variant& response) const
 {
-    auto const tag = dictFind<int>(&response, TR_KEY_tag);
-    return tag ? *tag : -1;
+    return dictFind<int>(&response, TR_KEY_tag).value_or(-1);
 }
 
 RpcResponse RpcClient::parseResponseData(tr_variant& response) const
diff --git a/qt/RpcClient.h b/qt/RpcClient.h
index 14bd4088d..de003164c 100644
--- a/qt/RpcClient.h
+++ b/qt/RpcClient.h
@@ -82,8 +82,8 @@ private:
 
     void sendNetworkRequest(TrVariantPtr json, QFutureInterface<RpcResponse> const& promise);
     void sendLocalRequest(TrVariantPtr json, QFutureInterface<RpcResponse> const& promise, int64_t tag);
-    int64_t parseResponseTag(tr_variant& response) const;
-    RpcResponse parseResponseData(tr_variant& response) const;
+    [[nodiscard]] int64_t parseResponseTag(tr_variant& response) const;
+    [[nodiscard]] RpcResponse parseResponseData(tr_variant& response) const;
 
     static void localSessionCallback(tr_session* s, tr_variant* response, void* vself) noexcept;
 
diff --git a/qt/RpcQueue.cc b/qt/RpcQueue.cc
index 6ca68d329..3f7c0c3cf 100644
--- a/qt/RpcQueue.cc
+++ b/qt/RpcQueue.cc
@@ -7,12 +7,8 @@
 
 #include "RpcQueue.h"
 
-// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
-RpcQueue::Tag RpcQueue::next_tag = {};
-
 RpcQueue::RpcQueue(QObject* parent)
     : QObject(parent)
-    , tag_(next_tag++)
 {
     connect(&future_watcher_, &QFutureWatcher<RpcResponse>::finished, this, &RpcQueue::stepFinished);
 }
diff --git a/qt/RpcQueue.h b/qt/RpcQueue.h
index b35456413..a0d57988f 100644
--- a/qt/RpcQueue.h
+++ b/qt/RpcQueue.h
@@ -146,8 +146,9 @@ private:
         return promise.future();
     }
 
-    Tag const tag_;
-    static Tag next_tag;
+    static inline Tag next_tag = {};
+
+    Tag const tag_ = next_tag++;
     bool tolerate_errors_ = {};
     QFutureInterface<RpcResponse> promise_;
     QQueue<QPair<QueuedFunction, ErrorHandlerFunction>> queue_;
diff --git a/qt/Session.cc b/qt/Session.cc
index 98f090bda..fa61a6e6e 100644
--- a/qt/Session.cc
+++ b/qt/Session.cc
@@ -486,10 +486,8 @@ void Session::torrentRenamePath(torrent_ids_t const& torrent_ids, QString const&
         [this, &args]() { return exec("torrent-rename-path", &args); },
         [](RpcResponse const& r)
         {
-            auto str = dictFind<QString>(r.args.get(), TR_KEY_path);
-            auto const path = str ? *str : QStringLiteral("(unknown)");
-            str = dictFind<QString>(r.args.get(), TR_KEY_name);
-            auto const name = str ? *str : QStringLiteral("(unknown)");
+            auto const path = dictFind<QString>(r.args.get(), TR_KEY_path).value_or(QStringLiteral("(unknown)"));
+            auto const name = dictFind<QString>(r.args.get(), TR_KEY_name).value_or(QStringLiteral("(unknown)"));
 
             auto* d = new QMessageBox(
                 QMessageBox::Information,
diff --git a/qt/TrackerModelFilter.h b/qt/TrackerModelFilter.h
index 7d4f1badc..8a571ea1b 100644
--- a/qt/TrackerModelFilter.h
+++ b/qt/TrackerModelFilter.h
@@ -26,7 +26,7 @@ public:
 
 protected:
     // QSortFilterProxyModel
-    virtual bool filterAcceptsRow(int source_row, QModelIndex const& source_parent) const override;
+    bool filterAcceptsRow(int source_row, QModelIndex const& source_parent) const override;
 
 private:
     bool show_backups_ = {};
diff --git a/qt/VariantHelpers.h b/qt/VariantHelpers.h
index 58fc86c61..035af3769 100644
--- a/qt/VariantHelpers.h
+++ b/qt/VariantHelpers.h
@@ -24,10 +24,7 @@ struct Peer;
 struct TorrentFile;
 struct TrackerStat;
 
-namespace trqt
-{
-
-namespace variant_helpers
+namespace trqt::variant_helpers
 {
 
 template<typename T, typename std::enable_if_t<std::is_same_v<T, bool>>* = nullptr>
@@ -223,6 +220,4 @@ void dictAdd(tr_variant* dict, tr_quark key, T const& value)
     variantInit(tr_variantDictAdd(dict, key), value);
 }
 
-} // namespace variant_helpers
-
-} // namespace trqt
+} // namespace trqt::variant_helpers
diff --git a/utils/edit.cc b/utils/edit.cc
index 25ac3d91e..b261ae8e5 100644
--- a/utils/edit.cc
+++ b/utils/edit.cc
@@ -172,7 +172,7 @@ static std::string replaceSubstr(std::string_view str, std::string_view oldval,
     {
         auto const pos = str.find(oldval);
         ret += str.substr(0, pos);
-        if (pos == str.npos)
+        if (pos == std::string_view::npos)
         {
             break;
         }
@@ -240,8 +240,7 @@ static bool announce_list_has_url(tr_variant* announce_list, char const* url)
 
         while ((node = tr_variantListChild(tier, nodeCount)) != nullptr)
         {
-            auto sv = std::string_view{};
-            if (tr_variantGetStrView(node, &sv) && sv == url)
+            if (auto sv = std::string_view{}; tr_variantGetStrView(node, &sv) && sv == url)
             {
                 return true;
             }
diff --git a/utils/remote.cc b/utils/remote.cc
index 612351199..4f144930b 100644
--- a/utils/remote.cc
+++ b/utils/remote.cc
@@ -907,11 +907,11 @@ static std::string getStatusString(tr_variant* t)
     }
 }
 
-static char const* bandwidthPriorityNames[] = {
-    "Low",
-    "Normal",
-    "High",
-    "Invalid",
+static auto constexpr bandwidth_priority_names = std::array<std::string_view, 4>{
+    "Low"sv,
+    "Normal"sv,
+    "High"sv,
+    "Invalid"sv,
 };
 
 static char* format_date(char* buf, size_t buflen, time_t now)
@@ -1241,7 +1241,7 @@ static void printDetails(tr_variant* top)
 
             if (tr_variantDictFindInt(t, TR_KEY_bandwidthPriority, &i))
             {
-                fmt::print("  Bandwidth Priority: {:s}\n", bandwidthPriorityNames[(i + 1) & 3]);
+                fmt::print("  Bandwidth Priority: {:s}\n", bandwidth_priority_names[(i + 1) & 3]);
             }
 
             fmt::print("\n");