diff --git a/gtk/Application.cc b/gtk/Application.cc
index 4dff344a9..703a48ff0 100644
--- a/gtk/Application.cc
+++ b/gtk/Application.cc
@@ -813,9 +813,7 @@ void Application::Impl::on_drag_data_received(
     guint /*info*/,
     guint time_)
 {
-    auto const uris = selection_data.get_uris();
-
-    if (!uris.empty())
+    if (auto const uris = selection_data.get_uris(); !uris.empty())
     {
         auto files = std::vector<Glib::RefPtr<Gio::File>>();
         files.reserve(uris.size());
diff --git a/libtransmission/completion.cc b/libtransmission/completion.cc
index 9f51e33c4..e98837ee7 100644
--- a/libtransmission/completion.cc
+++ b/libtransmission/completion.cc
@@ -7,6 +7,7 @@
  */
 
 #include <algorithm>
+#include <memory>
 #include <vector>
 
 #include "transmission.h"
@@ -134,13 +135,12 @@ std::vector<uint8_t> tr_completion::createPieceBitfield() const
     size_t const n = block_info_->n_pieces;
     auto pieces = tr_bitfield{ n };
 
-    bool* const flags = new bool[n];
+    auto flags = std::make_unique<bool[]>(n);
     for (tr_piece_index_t piece = 0; piece < n; ++piece)
     {
         flags[piece] = hasPiece(piece);
     }
-    pieces.setFromBools(flags, n);
-    delete[] flags;
+    pieces.setFromBools(flags.get(), n);
 
     return pieces.raw();
 }
diff --git a/libtransmission/completion.h b/libtransmission/completion.h
index 33eaad175..ebdbd3827 100644
--- a/libtransmission/completion.h
+++ b/libtransmission/completion.h
@@ -30,6 +30,8 @@ struct tr_completion
     struct torrent_view
     {
         virtual bool pieceIsDnd(tr_piece_index_t piece) const = 0;
+
+        virtual ~torrent_view() = default;
     };
 
     explicit tr_completion(torrent_view const* tor, tr_block_info const* block_info)
diff --git a/libtransmission/peer-io.cc b/libtransmission/peer-io.cc
index 00bd40708..880b7c1d4 100644
--- a/libtransmission/peer-io.cc
+++ b/libtransmission/peer-io.cc
@@ -195,7 +195,7 @@ static void canReadWrapper(tr_peerIo* io)
 
     tr_peerIoRef(io);
 
-    tr_session* const session = io->session;
+    tr_session const* const session = io->session;
 
     /* try to consume the input buffer */
     if (io->canRead != nullptr)
diff --git a/libtransmission/peer-mgr-wishlist.cc b/libtransmission/peer-mgr-wishlist.cc
index bfbae912b..c661d751b 100644
--- a/libtransmission/peer-mgr-wishlist.cc
+++ b/libtransmission/peer-mgr-wishlist.cc
@@ -102,7 +102,7 @@ std::vector<Candidate> getCandidates(Wishlist::PeerInfo const& peer_info)
     return candidates;
 }
 
-static std::vector<tr_block_span_t> makeSpans(tr_block_index_t const* sorted_blocks, size_t n_blocks)
+std::vector<tr_block_span_t> makeSpans(tr_block_index_t const* sorted_blocks, size_t n_blocks)
 {
     if (n_blocks == 0)
     {
@@ -130,7 +130,7 @@ static std::vector<tr_block_span_t> makeSpans(tr_block_index_t const* sorted_blo
 
 } // namespace
 
-std::vector<tr_block_span_t> Wishlist::next(Wishlist::PeerInfo const& peer_info, size_t n_wanted_blocks)
+std::vector<tr_block_span_t> Wishlist::next(Wishlist::PeerInfo const& peer_info, size_t n_wanted_blocks) const
 {
     size_t n_blocks = 0;
     auto spans = std::vector<tr_block_span_t>{};
@@ -167,8 +167,7 @@ std::vector<tr_block_span_t> Wishlist::next(Wishlist::PeerInfo const& peer_info,
 
             // don't request from too many peers
             size_t const n_peers = peer_info.countActiveRequests(block);
-            size_t const max_peers = peer_info.isEndgame() ? 2 : 1;
-            if (n_peers >= max_peers)
+            if (size_t const max_peers = peer_info.isEndgame() ? 2 : 1; n_peers >= max_peers)
             {
                 continue;
             }
diff --git a/libtransmission/peer-mgr-wishlist.h b/libtransmission/peer-mgr-wishlist.h
index b3f47b162..e1cf8da38 100644
--- a/libtransmission/peer-mgr-wishlist.h
+++ b/libtransmission/peer-mgr-wishlist.h
@@ -31,8 +31,9 @@ public:
         virtual tr_block_span_t blockSpan(tr_piece_index_t) const = 0;
         virtual tr_piece_index_t countAllPieces() const = 0;
         virtual tr_priority_t priority(tr_piece_index_t) const = 0;
+        virtual ~PeerInfo() = default;
     };
 
     // get a list of the next blocks that we should request from a peer
-    std::vector<tr_block_span_t> next(PeerInfo const& peer_info, size_t n_wanted_blocks);
+    std::vector<tr_block_span_t> next(PeerInfo const& peer_info, size_t n_wanted_blocks) const;
 };
diff --git a/libtransmission/peer-mgr.cc b/libtransmission/peer-mgr.cc
index 4bedbd7b9..a3fb85005 100644
--- a/libtransmission/peer-mgr.cc
+++ b/libtransmission/peer-mgr.cc
@@ -506,8 +506,8 @@ void tr_peerMgrSetUtpFailed(tr_torrent* tor, tr_address const* addr, bool failed
 ***
 *** 1. tr_swarm::active_requests, an opaque class that tracks what requests
 ***    we currently have, i.e. which blocks and from which peers.
-***    This is used for (a) cancelling requests that have been waiting
-***    for too long and (b) avoiding duplicate requests.
+***    This is used for cancelling requests that have been waiting
+***    for too long and avoiding duplicate requests.
 ***
 *** 2. tr_swarm::pieces, an array of "struct weighted_piece" which lists the
 ***    pieces that we want to request. It's used to decide which blocks to
@@ -541,7 +541,6 @@ static int countActiveWebseeds(tr_swarm* s)
 // TODO: if we keep this, add equivalent API to ActiveRequest
 void tr_peerMgrClientSentRequests(tr_torrent* torrent, tr_peer* peer, tr_block_span_t span)
 {
-    // std::cout << __FILE__ << ':' << __LINE__ << " tr_peerMgrClientSentRequests [" << range.begin << "..." << range.end << ')' << std::endl;
     auto const now = tr_time();
 
     for (tr_block_index_t block = span.begin; block < span.end; ++block)
@@ -569,6 +568,8 @@ std::vector<tr_block_span_t> tr_peerMgrGetNextRequests(tr_torrent* torrent, tr_p
         {
         }
 
+        ~PeerInfoImpl() override = default;
+
         bool clientCanRequestBlock(tr_block_index_t block) const override
         {
             return !torrent_->hasBlock(block) && !swarm_->active_requests.has(block, peer_);
diff --git a/libtransmission/peer-msgs.cc b/libtransmission/peer-msgs.cc
index 5979a0f9b..ce35e8cea 100644
--- a/libtransmission/peer-msgs.cc
+++ b/libtransmission/peer-msgs.cc
@@ -2085,7 +2085,6 @@ static void updateBlockRequests(tr_peerMsgsImpl* msgs)
     TR_ASSERT(msgs->is_client_interested());
     TR_ASSERT(!msgs->is_client_choked());
 
-    // std::cout << __FILE__ << ':' << __LINE__ << " wants " << n_wanted << " blocks to request" << std::endl;
     for (auto const span : tr_peerMgrGetNextRequests(msgs->torrent, msgs, n_wanted))
     {
         for (tr_block_index_t block = span.begin; block < span.end; ++block)
@@ -2093,7 +2092,6 @@ static void updateBlockRequests(tr_peerMsgsImpl* msgs)
             protocolSendRequest(msgs, blockToReq(msgs->torrent, block));
         }
 
-        // std::cout << __FILE__ << ':' << __LINE__ << " peer " << (void*)msgs << " requested " << span.end - span.begin << " blocks" << std::endl;
         tr_peerMgrClientSentRequests(msgs->torrent, msgs, span);
     }
 }
diff --git a/libtransmission/torrent-ctor.cc b/libtransmission/torrent-ctor.cc
index c4abc47c3..25f1e1180 100644
--- a/libtransmission/torrent-ctor.cc
+++ b/libtransmission/torrent-ctor.cc
@@ -131,8 +131,7 @@ int tr_ctorSetMetainfoFromFile(tr_ctor* ctor, char const* filename)
         return EILSEQ;
     }
 
-    int const err = parseMetainfoContents(ctor);
-    if (err)
+    if (int const err = parseMetainfoContents(ctor); err != 0)
     {
         clearMetainfo(ctor);
         return err;
@@ -141,9 +140,7 @@ int tr_ctorSetMetainfoFromFile(tr_ctor* ctor, char const* filename)
     setSourceFile(ctor, filename);
 
     /* if no `name' field was set, then set it from the filename */
-    tr_variant* info = nullptr;
-
-    if (tr_variantDictFindDict(&ctor->metainfo, TR_KEY_info, &info))
+    if (tr_variant* info = nullptr; tr_variantDictFindDict(&ctor->metainfo, TR_KEY_info, &info))
     {
         auto name = std::string_view{};
 
diff --git a/libtransmission/torrent.cc b/libtransmission/torrent.cc
index 2e64b7551..8559db08c 100644
--- a/libtransmission/torrent.cc
+++ b/libtransmission/torrent.cc
@@ -7,6 +7,7 @@
  */
 
 #include <algorithm> /* EINVAL */
+#include <array>
 #include <cerrno> /* EINVAL */
 #include <climits> /* INT_MAX */
 #include <cmath>
@@ -1932,7 +1933,7 @@ static void torrentCallScript(tr_torrent const* tor, char const* script)
 
     char* const torrent_dir = tr_sys_path_native_separators(tr_strdup(tor->currentDir));
 
-    char const* const cmd[] = {
+    auto const cmd = std::array<char const*, 2>{
         script,
         nullptr,
     };
@@ -1952,7 +1953,7 @@ static void torrentCallScript(tr_torrent const* tor, char const* script)
 
     tr_error* error = nullptr;
 
-    if (!tr_spawn_async(cmd, env, TR_IF_WIN32("\\", "/"), &error))
+    if (!tr_spawn_async(std::data(cmd), env, TR_IF_WIN32("\\", "/"), &error))
     {
         tr_logAddTorErr(tor, "Error executing script \"%s\" (%d): %s", script, error->code, error->message);
         tr_error_free(error);
diff --git a/libtransmission/torrent.h b/libtransmission/torrent.h
index b0f3ba10c..0cad3ea29 100644
--- a/libtransmission/torrent.h
+++ b/libtransmission/torrent.h
@@ -134,7 +134,7 @@ public:
     {
     }
 
-    virtual ~tr_torrent() = default;
+    virtual ~tr_torrent() override = default;
 
     void setLocation(
         std::string_view location,
@@ -161,7 +161,6 @@ public:
     // private:
     void swapMetainfo(tr_metainfo_parsed& parsed);
 
-public:
     auto unique_lock() const
     {
         return session->unique_lock();
@@ -337,7 +336,6 @@ public:
 
     std::optional<tr_found_file_t> findFile(std::string& filename, tr_file_index_t i) const;
 
-public:
     tr_info info = {};
 
     tr_bitfield dnd_pieces_ = tr_bitfield{ 0 };
diff --git a/libtransmission/tr-dht.cc b/libtransmission/tr-dht.cc
index 853532a32..92ffa2482 100644
--- a/libtransmission/tr-dht.cc
+++ b/libtransmission/tr-dht.cc
@@ -365,8 +365,7 @@ int tr_dhtInit(tr_session* ss)
         tr_rand_buffer(myid, 20);
     }
 
-    int rc = dht_init(ss->udp_socket, ss->udp6_socket, myid, nullptr);
-    if (rc < 0)
+    if (int rc = dht_init(ss->udp_socket, ss->udp6_socket, myid, nullptr); rc < 0)
     {
         tr_free(nodes6);
         tr_free(nodes);
diff --git a/libtransmission/variant-benc.cc b/libtransmission/variant-benc.cc
index 123e4fbe1..01abe1045 100644
--- a/libtransmission/variant-benc.cc
+++ b/libtransmission/variant-benc.cc
@@ -186,50 +186,43 @@ int tr_variantParseBenc(tr_variant& top, int parse_opts, std::string_view benc,
                     break;
                 }
 
-                tr_variant* const v = get_node(stack, key, &top, &err);
-                if (v != nullptr)
+                if (tr_variant* const v = get_node(stack, key, &top, &err); v != nullptr)
                 {
                     tr_variantInitInt(v, *value);
                 }
                 break;
             }
         case 'l': // list
-            {
-                benc.remove_prefix(1);
+            benc.remove_prefix(1);
 
-                tr_variant* const v = get_node(stack, key, &top, &err);
-                if (v != nullptr)
-                {
-                    tr_variantInitList(v, 0);
-                    stack.push_back(v);
-                }
-                break;
+            if (tr_variant* const v = get_node(stack, key, &top, &err); v != nullptr)
+            {
+                tr_variantInitList(v, 0);
+                stack.push_back(v);
             }
+            break;
+
         case 'd': // dict
-            {
-                benc.remove_prefix(1);
+            benc.remove_prefix(1);
 
-                tr_variant* const v = get_node(stack, key, &top, &err);
-                if (v != nullptr)
-                {
-                    tr_variantInitDict(v, 0);
-                    stack.push_back(v);
-                }
-                break;
+            if (tr_variant* const v = get_node(stack, key, &top, &err); v != nullptr)
+            {
+                tr_variantInitDict(v, 0);
+                stack.push_back(v);
             }
+            break;
         case 'e': // end of list or dict
+            benc.remove_prefix(1);
+
+            if (std::empty(stack) || key)
             {
-                benc.remove_prefix(1);
-
-                if (std::empty(stack) || key)
-                {
-                    err = EILSEQ;
-                    break;
-                }
-
-                stack.pop_back();
+                err = EILSEQ;
                 break;
             }
+
+            stack.pop_back();
+            break;
+
         case '0':
         case '1':
         case '2':
diff --git a/qt/FileTreeModel.cc b/qt/FileTreeModel.cc
index 54cb1afba..cf8f1aa47 100644
--- a/qt/FileTreeModel.cc
+++ b/qt/FileTreeModel.cc
@@ -92,7 +92,7 @@ public:
 
 FileTreeModel::FileTreeModel(QObject* parent, bool is_editable)
     : QAbstractItemModel{ parent }
-    , root_item_{ new FileTreeItem }
+    , root_item_{ std::make_unique<FileTreeItem>() }
     , is_editable_{ is_editable }
 {
 }
@@ -100,8 +100,6 @@ FileTreeModel::FileTreeModel(QObject* parent, bool is_editable)
 FileTreeModel::~FileTreeModel()
 {
     clear();
-
-    delete root_item_;
 }
 
 void FileTreeModel::setEditable(bool is_editable)
@@ -233,7 +231,7 @@ QModelIndex FileTreeModel::index(int row, int column, QModelIndex const& parent)
 
         if (!parent.isValid())
         {
-            parent_item = root_item_;
+            parent_item = root_item_.get();
         }
         else
         {
@@ -270,7 +268,7 @@ QModelIndex FileTreeModel::parent(QModelIndex const& child, int column) const
 
 int FileTreeModel::rowCount(QModelIndex const& parent) const
 {
-    FileTreeItem const* parent_item = parent.isValid() ? itemFromIndex(parent) : root_item_;
+    FileTreeItem const* parent_item = parent.isValid() ? itemFromIndex(parent) : root_item_.get();
 
     return parent_item->childCount();
 }
@@ -284,7 +282,7 @@ int FileTreeModel::columnCount(QModelIndex const& parent) const
 
 QModelIndex FileTreeModel::indexOf(FileTreeItem* item, int column) const
 {
-    if (item == nullptr || item == root_item_)
+    if (item == nullptr || item == root_item_.get())
     {
         return QModelIndex();
     }
@@ -320,8 +318,7 @@ void FileTreeModel::clear()
 {
     beginResetModel();
     clearSubtree(QModelIndex());
-    delete root_item_;
-    root_item_ = new FileTreeItem{};
+    root_item_ = std::make_unique<FileTreeItem>();
     endResetModel();
 
     assert(index_cache_.isEmpty());
@@ -368,7 +365,7 @@ void FileTreeModel::addFile(
             item = item->parent();
         }
 
-        assert(item == root_item_);
+        assert(item == root_item_.get());
 
         if (index_with_changed_parents.isValid())
         {
@@ -379,7 +376,7 @@ void FileTreeModel::addFile(
     {
         bool added = false;
 
-        item = root_item_;
+        item = root_item_.get();
         BackwardPathIterator filename_it(filename);
 
         while (filename_it.hasNext())
@@ -411,7 +408,7 @@ void FileTreeModel::addFile(
             item = child;
         }
 
-        if (item != root_item_)
+        if (item != root_item_.get())
         {
             assert(item->fileIndex() == file_index);
             assert(item->totalSize() == total_size);
diff --git a/qt/FileTreeModel.h b/qt/FileTreeModel.h
index 8a7390c6f..5c214049e 100644
--- a/qt/FileTreeModel.h
+++ b/qt/FileTreeModel.h
@@ -9,6 +9,7 @@
 #pragma once
 
 #include <cstdint> // uint64_t
+#include <memory>
 
 #include <QAbstractItemModel>
 #include <QMap>
@@ -98,6 +99,6 @@ private:
     QModelIndexList getOrphanIndices(QModelIndexList const& indices) const;
 
     QMap<int, FileTreeItem*> index_cache_;
-    FileTreeItem* root_item_ = {};
+    std::unique_ptr<FileTreeItem> root_item_;
     bool is_editable_ = {};
 };
diff --git a/qt/VariantHelpers.h b/qt/VariantHelpers.h
index 6f37e5783..bad7876e3 100644
--- a/qt/VariantHelpers.h
+++ b/qt/VariantHelpers.h
@@ -77,8 +77,8 @@ template<typename T, typename std::enable_if<std::is_same_v<T, QString>>::type*
 auto getValue(tr_variant const* variant)
 {
     std::optional<T> ret;
-    auto sv = std::string_view{};
-    if (tr_variantGetStrView(variant, &sv))
+
+    if (auto sv = std::string_view{}; tr_variantGetStrView(variant, &sv))
     {
         ret = QString::fromUtf8(std::data(sv), std::size(sv));
     }
@@ -90,8 +90,8 @@ template<typename T, typename std::enable_if<std::is_same_v<T, std::string_view>
 auto getValue(tr_variant const* variant)
 {
     std::optional<T> ret;
-    auto sv = std::string_view{};
-    if (tr_variantGetStrView(variant, &sv))
+
+    if (auto sv = std::string_view{}; tr_variantGetStrView(variant, &sv))
     {
         ret = std::string_view(std::data(sv), std::size(sv));
     }
@@ -181,8 +181,8 @@ template<typename T>
 auto dictFind(tr_variant* dict, tr_quark key)
 {
     std::optional<T> ret;
-    auto const* child = tr_variantDictFind(dict, key);
-    if (child != nullptr)
+
+    if (auto const* child = tr_variantDictFind(dict, key); child != nullptr)
     {
         ret = getValue<T>(child);
     }