diff --git a/gtk/PathButton.cc b/gtk/PathButton.cc
index ee840ecb0..f8cc49298 100644
--- a/gtk/PathButton.cc
+++ b/gtk/PathButton.cc
@@ -13,7 +13,7 @@
 class PathButton::Impl
 {
 public:
-    Impl(PathButton& widget);
+    explicit Impl(PathButton& widget);
 
     TR_DISABLE_COPY_MOVE(Impl)
 
diff --git a/gtk/Utils.cc b/gtk/Utils.cc
index 483dc9ae3..283e14255 100644
--- a/gtk/Utils.cc
+++ b/gtk/Utils.cc
@@ -286,9 +286,9 @@ bool on_tree_view_button_pressed(
     if (context_menu_requested)
     {
         Gtk::TreeModel::Path path;
-        auto const selection = view.get_selection();
 
-        if (view.get_path_at_pos((int)view_x, (int)view_y, path) && !selection->is_selected(path))
+        if (auto const selection = view.get_selection();
+            view.get_path_at_pos((int)view_x, (int)view_y, path) && !selection->is_selected(path))
         {
             selection->unselect_all();
             selection->select(path);
@@ -707,8 +707,8 @@ void gtr_paste_clipboard_url_into_entry(Gtk::Entry& entry)
 {
     auto const process = [&entry](Glib::ustring const& text)
     {
-        auto const sv = tr_strvStrip(text.raw());
-        if (!sv.empty() && (tr_urlIsValid(sv) || tr_magnet_metainfo{}.parseMagnet(sv)))
+        if (auto const sv = tr_strvStrip(text.raw());
+            !sv.empty() && (tr_urlIsValid(sv) || tr_magnet_metainfo{}.parseMagnet(sv)))
         {
             entry.set_text(text);
             return true;
diff --git a/libtransmission/dns-ev.h b/libtransmission/dns-ev.h
index 29275104f..1750513bf 100644
--- a/libtransmission/dns-ev.h
+++ b/libtransmission/dns-ev.h
@@ -22,8 +22,6 @@
 #include "dns.h"
 #include "utils.h" // for tr_strlower()
 
-using namespace std::literals;
-
 namespace libtransmission
 {
 
@@ -107,7 +105,8 @@ public:
         }
 
         auto& request = requests_[key];
-        auto const tag = next_tag_++;
+        auto const tag = next_tag_;
+        ++next_tag_;
         request.callbacks.emplace_back(tag, std::move(callback));
         if (request.request == nullptr)
         {
diff --git a/libtransmission/net.cc b/libtransmission/net.cc
index 04fc3a8b1..3fe026878 100644
--- a/libtransmission/net.cc
+++ b/libtransmission/net.cc
@@ -321,7 +321,7 @@ struct tr_peer_socket tr_netOpenPeerSocket(tr_session* session, tr_address const
     auto const [source_addr, is_default_addr] = session->publicAddress(addr->type);
     auto const [source_sock, sourcelen] = source_addr.toSockaddr({});
 
-    if (bind(s, (struct sockaddr*)&source_sock, sourcelen) == -1)
+    if (bind(s, reinterpret_cast<sockaddr const*>(&source_sock), sourcelen) == -1)
     {
         tr_logAddWarn(fmt::format(
             _("Couldn't set source address {address} on {socket}: {error} ({error_code})"),
@@ -334,7 +334,7 @@ struct tr_peer_socket tr_netOpenPeerSocket(tr_session* session, tr_address const
     }
 
     auto ret = tr_peer_socket{};
-    if (connect(s, (struct sockaddr*)&sock, addrlen) == -1 &&
+    if (connect(s, reinterpret_cast<sockaddr const*>(&sock), addrlen) == -1 &&
 #ifdef _WIN32
         sockerrno != WSAEWOULDBLOCK &&
 #endif
diff --git a/libtransmission/net.h b/libtransmission/net.h
index 30075408c..cfbf41928 100644
--- a/libtransmission/net.h
+++ b/libtransmission/net.h
@@ -142,7 +142,7 @@ public:
     }
 
 private:
-    constexpr tr_port(uint16_t hport) noexcept
+    explicit constexpr tr_port(uint16_t hport) noexcept
         : hport_{ hport }
     {
     }
diff --git a/libtransmission/peer-io.cc b/libtransmission/peer-io.cc
index db0fbad87..fa9930718 100644
--- a/libtransmission/peer-io.cc
+++ b/libtransmission/peer-io.cc
@@ -205,8 +205,7 @@ static void event_read_cb(evutil_socket_t fd, short /*event*/, void* vio)
     }
 
     tr_error* error = nullptr;
-    auto const res = io->inbuf.addSocket(fd, howmuch, &error);
-    if (res > 0)
+    if (auto const res = io->inbuf.addSocket(fd, howmuch, &error); res > 0)
     {
         io->setEnabled(dir, true);
 
diff --git a/libtransmission/session.cc b/libtransmission/session.cc
index c4eac5f84..4bb9a0170 100644
--- a/libtransmission/session.cc
+++ b/libtransmission/session.cc
@@ -290,7 +290,7 @@ static void acceptIncomingPeer(evutil_socket_t fd, short /*what*/, void* vsessio
 
     if (auto const incoming_info = tr_netAccept(session, fd); incoming_info)
     {
-        auto const [addr, port, sock] = *incoming_info;
+        auto const& [addr, port, sock] = *incoming_info;
         tr_logAddTrace(fmt::format("new incoming connection {} ({})", sock, addr.readable(port)));
         session->addIncoming(addr, port, tr_peer_socket_tcp_create(sock));
     }
diff --git a/libtransmission/session.h b/libtransmission/session.h
index 6792cbbd4..8221e7d5f 100644
--- a/libtransmission/session.h
+++ b/libtransmission/session.h
@@ -143,7 +143,7 @@ private:
     class AnnouncerUdpMediator final : public tr_announcer_udp::Mediator
     {
     public:
-        AnnouncerUdpMediator(tr_session& session)
+        explicit AnnouncerUdpMediator(tr_session& session)
             : session_{ session }
         {
         }
diff --git a/libtransmission/timer-ev.h b/libtransmission/timer-ev.h
index 64295c4e2..7ed849dc2 100644
--- a/libtransmission/timer-ev.h
+++ b/libtransmission/timer-ev.h
@@ -20,7 +20,7 @@ namespace libtransmission
 class EvTimerMaker final : public TimerMaker
 {
 public:
-    EvTimerMaker(event_base* base)
+    explicit EvTimerMaker(event_base* base)
         : event_base_{ base }
     {
     }
diff --git a/libtransmission/tr-buffer.h b/libtransmission/tr-buffer.h
index bfe011d97..484f84828 100644
--- a/libtransmission/tr-buffer.h
+++ b/libtransmission/tr-buffer.h
@@ -125,7 +125,7 @@ public:
     Buffer& operator=(Buffer&&) = default;
 
     template<typename T>
-    Buffer(T const& data)
+    explicit Buffer(T const& data)
     {
         add(std::data(data), std::size(data));
     }
@@ -137,7 +137,7 @@ public:
 
     [[nodiscard]] auto empty() const noexcept
     {
-        return size() == 0U;
+        return evbuffer_get_length(buf_.get()) == 0;
     }
 
     [[nodiscard]] auto vecs(size_t n_bytes) const
diff --git a/libtransmission/tr-utp.cc b/libtransmission/tr-utp.cc
index 64b80ef87..d49dc7f8c 100644
--- a/libtransmission/tr-utp.cc
+++ b/libtransmission/tr-utp.cc
@@ -92,7 +92,7 @@ static void utp_on_accept(tr_session* const session, UTPSocket* const utp_sock)
 
     if (auto addrport = tr_address::fromSockaddr(reinterpret_cast<struct sockaddr*>(&from_storage)); addrport)
     {
-        auto const [addr, port] = *addrport;
+        auto const& [addr, port] = *addrport;
         session->addIncoming(addr, port, tr_peer_socket_utp_create(utp_sock));
     }
     else