diff --git a/src/app/application.cpp b/src/app/application.cpp
index da09211bd..0cc5dda46 100644
--- a/src/app/application.cpp
+++ b/src/app/application.cpp
@@ -543,7 +543,7 @@ void Application::runExternalProgram(const QString &programTemplate, const BitTo
 
     const auto replaceVariables = [torrent](QString str) -> QString
     {
-        for (int i = (str.length() - 2); i >= 0; --i)
+        for (qsizetype i = (str.length() - 2); i >= 0; --i)
         {
             if (str[i] != u'%')
                 continue;
diff --git a/src/app/cmdoptions.cpp b/src/app/cmdoptions.cpp
index 84f50e988..cb4ce6c01 100644
--- a/src/app/cmdoptions.cpp
+++ b/src/app/cmdoptions.cpp
@@ -356,7 +356,7 @@ QBtCommandLineParameters parseCommandLine(const QStringList &args)
 {
     QBtCommandLineParameters result {QProcessEnvironment::systemEnvironment()};
 
-    for (int i = 1; i < args.count(); ++i)
+    for (qsizetype i = 1; i < args.count(); ++i)
     {
         const QString &arg = args[i];
 
diff --git a/src/base/bittorrent/dbresumedatastorage.cpp b/src/base/bittorrent/dbresumedatastorage.cpp
index 4c6a3576c..76479ac15 100644
--- a/src/base/bittorrent/dbresumedatastorage.cpp
+++ b/src/base/bittorrent/dbresumedatastorage.cpp
@@ -170,8 +170,8 @@ namespace
 
     std::pair<QString, QString> joinColumns(const QList<Column> &columns)
     {
-        int namesSize = columns.size();
-        int valuesSize = columns.size();
+        qsizetype namesSize = columns.size();
+        qsizetype valuesSize = columns.size();
         for (const Column &column : columns)
         {
             namesSize += column.name.size() + 2;
diff --git a/src/base/bittorrent/peerinfo.cpp b/src/base/bittorrent/peerinfo.cpp
index 3706b1e81..5d9abbec6 100644
--- a/src/base/bittorrent/peerinfo.cpp
+++ b/src/base/bittorrent/peerinfo.cpp
@@ -273,12 +273,12 @@ QString PeerInfo::connectionType() const
 
 qreal PeerInfo::calcRelevance(const QBitArray &allPieces) const
 {
-    const int localMissing = allPieces.count(false);
+    const qsizetype localMissing = allPieces.count(false);
     if (localMissing <= 0)
         return 0;
 
     const QBitArray peerPieces = pieces();
-    const int remoteHaves = (peerPieces & (~allPieces)).count(true);
+    const qsizetype remoteHaves = (peerPieces & (~allPieces)).count(true);
     return static_cast<qreal>(remoteHaves) / localMissing;
 }
 
diff --git a/src/base/bittorrent/sessionimpl.cpp b/src/base/bittorrent/sessionimpl.cpp
index 13176a39e..d771b132b 100644
--- a/src/base/bittorrent/sessionimpl.cpp
+++ b/src/base/bittorrent/sessionimpl.cpp
@@ -404,7 +404,7 @@ bool Session::isValidCategoryName(const QString &name)
 
 QString Session::subcategoryName(const QString &category)
 {
-    const int sepIndex = category.lastIndexOf(u'/');
+    const qsizetype sepIndex = category.lastIndexOf(u'/');
     if (sepIndex >= 0)
         return category.sliced(sepIndex + 1);
 
@@ -413,7 +413,7 @@ QString Session::subcategoryName(const QString &category)
 
 QString Session::parentCategoryName(const QString &category)
 {
-    const int sepIndex = category.lastIndexOf(u'/');
+    const qsizetype sepIndex = category.lastIndexOf(u'/');
     if (sepIndex >= 0)
         return category.first(sepIndex);
 
@@ -2843,7 +2843,7 @@ bool SessionImpl::addTorrent_impl(const TorrentDescriptor &source, const AddTorr
 
         if (!filePriorities.isEmpty())
         {
-            for (int i = 0; i < filePriorities.size(); ++i)
+            for (qsizetype i = 0; i < filePriorities.size(); ++i)
                 p.file_priorities[LT::toUnderlyingType(nativeIndexes[i])] = LT::toNative(filePriorities[i]);
         }
 
@@ -2944,7 +2944,7 @@ bool SessionImpl::addTorrent_impl(const TorrentDescriptor &source, const AddTorr
         {
             const TorrentInfo torrentInfo {*p.ti};
             const auto nativeIndexes = torrentInfo.nativeIndexes();
-            for (int i = 0; i < result.fileNames.size(); ++i)
+            for (qsizetype i = 0; i < result.fileNames.size(); ++i)
                 p.renamed_files[nativeIndexes[i]] = result.fileNames[i].toString().toStdString();
         }
 
@@ -4146,7 +4146,7 @@ void SessionImpl::applyFilenameFilter(const PathList &files, QList<DownloadPrior
     };
 
     priorities.resize(files.count(), DownloadPriority::Normal);
-    for (int i = 0; i < priorities.size(); ++i)
+    for (qsizetype i = 0; i < priorities.size(); ++i)
     {
         if (priorities[i] == BitTorrent::DownloadPriority::Ignored)
             continue;
diff --git a/src/base/bittorrent/torrentdescriptor.cpp b/src/base/bittorrent/torrentdescriptor.cpp
index 7e89e5919..a79fa75d7 100644
--- a/src/base/bittorrent/torrentdescriptor.cpp
+++ b/src/base/bittorrent/torrentdescriptor.cpp
@@ -57,9 +57,10 @@ namespace
         //      == 20 (SHA-1 length in bytes) * 1.6 (the efficiency of Base32 encoding)
         const int V1_HEX_SIZE = SHA1Hash::length() * 2;
         const int V1_BASE32_SIZE = SHA1Hash::length() * 1.6;
+        const qsizetype strSize = string.size();
 
-        return ((((string.size() == V1_HEX_SIZE)) && !string.contains(QRegularExpression(u"[^0-9A-Fa-f]"_s)))
-                || ((string.size() == V1_BASE32_SIZE) && !string.contains(QRegularExpression(u"[^2-7A-Za-z]"_s))));
+        return (((strSize == V1_HEX_SIZE) && !string.contains(QRegularExpression(u"[^0-9A-Fa-f]"_s)))
+                || ((strSize == V1_BASE32_SIZE) && !string.contains(QRegularExpression(u"[^2-7A-Za-z]"_s))));
     }
 
     bool isV2Hash(const QString &string)
diff --git a/src/base/bittorrent/torrentimpl.cpp b/src/base/bittorrent/torrentimpl.cpp
index 181ac50c1..5a315bd93 100644
--- a/src/base/bittorrent/torrentimpl.cpp
+++ b/src/base/bittorrent/torrentimpl.cpp
@@ -1403,7 +1403,7 @@ QList<qreal> TorrentImpl::filesProgress() const
     if (!hasMetadata())
         return {};
 
-    const int count = m_filesProgress.size();
+    const qsizetype count = m_filesProgress.size();
     Q_ASSERT(count == filesCount());
     if (count != filesCount()) [[unlikely]]
         return {};
@@ -1710,7 +1710,7 @@ void TorrentImpl::applyFirstLastPiecePriority(const bool enabled)
 
     // Updating file priorities is an async operation in libtorrent, when we just updated it and immediately query it
     // we might get the old/wrong values, so we rely on `updatedFilePrio` in this case.
-    for (int fileIndex = 0; fileIndex < m_filePriorities.size(); ++fileIndex)
+    for (qsizetype fileIndex = 0; fileIndex < m_filePriorities.size(); ++fileIndex)
     {
         const DownloadPriority filePrio = m_filePriorities[fileIndex];
         if (filePrio <= DownloadPriority::Ignored)
@@ -1808,7 +1808,7 @@ void TorrentImpl::endReceivedMetadataHandling(const Path &savePath, const PathLi
     m_filesProgress.resize(filesCount());
     updateProgress();
 
-    for (int i = 0; i < fileNames.size(); ++i)
+    for (qsizetype i = 0; i < fileNames.size(); ++i)
     {
         const auto nativeIndex = nativeIndexes.at(i);
 
@@ -1822,7 +1822,7 @@ void TorrentImpl::endReceivedMetadataHandling(const Path &savePath, const PathLi
     }
 
     m_session->applyFilenameFilter(m_filePaths, m_filePriorities);
-    for (int i = 0; i < m_filePriorities.size(); ++i)
+    for (qsizetype i = 0; i < m_filePriorities.size(); ++i)
         p.file_priorities[LT::toUnderlyingType(nativeIndexes[i])] = LT::toNative(m_filePriorities[i]);
 
     p.save_path = savePath.toString().toStdString();
@@ -2152,7 +2152,7 @@ void TorrentImpl::handleSaveResumeData(lt::add_torrent_params params)
 
         const auto nativeIndexes = metadata.nativeIndexes();
         m_indexMap.reserve(filePaths.size());
-        for (int i = 0; i < filePaths.size(); ++i)
+        for (qsizetype i = 0; i < filePaths.size(); ++i)
         {
             const auto nativeIndex = nativeIndexes.at(i);
             m_indexMap[nativeIndex] = i;
@@ -2931,7 +2931,7 @@ void TorrentImpl::prioritizeFiles(const QList<DownloadPriority> &priorities)
     // Reset 'm_hasSeedStatus' if needed in order to react again to
     // "torrent finished" event and e.g. show tray notifications
     const QList<DownloadPriority> oldPriorities = filePriorities();
-    for (int i = 0; i < oldPriorities.size(); ++i)
+    for (qsizetype i = 0; i < oldPriorities.size(); ++i)
     {
         if ((oldPriorities[i] == DownloadPriority::Ignored)
             && (priorities[i] > DownloadPriority::Ignored)
@@ -2945,7 +2945,7 @@ void TorrentImpl::prioritizeFiles(const QList<DownloadPriority> &priorities)
     const int internalFilesCount = m_torrentInfo.nativeInfo()->files().num_files(); // including .pad files
     auto nativePriorities = std::vector<lt::download_priority_t>(internalFilesCount, LT::toNative(DownloadPriority::Normal));
     const auto nativeIndexes = m_torrentInfo.nativeIndexes();
-    for (int i = 0; i < priorities.size(); ++i)
+    for (qsizetype i = 0; i < priorities.size(); ++i)
         nativePriorities[LT::toUnderlyingType(nativeIndexes[i])] = LT::toNative(priorities[i]);
 
     qDebug() << Q_FUNC_INFO << "Changing files priorities...";
diff --git a/src/base/bittorrent/torrentinfo.cpp b/src/base/bittorrent/torrentinfo.cpp
index 590930fe2..eb7388643 100644
--- a/src/base/bittorrent/torrentinfo.cpp
+++ b/src/base/bittorrent/torrentinfo.cpp
@@ -184,7 +184,7 @@ QByteArray TorrentInfo::rawData() const
     if (!isValid()) return {};
 #ifdef QBT_USES_LIBTORRENT2
     const lt::span<const char> infoSection {m_nativeInfo->info_section()};
-    return {infoSection.data(), static_cast<int>(infoSection.size())};
+    return {infoSection.data(), static_cast<qsizetype>(infoSection.size())};
 #else
     return {m_nativeInfo->metadata().get(), m_nativeInfo->metadata_size()};
 #endif
@@ -214,7 +214,7 @@ QList<int> TorrentInfo::fileIndicesForPiece(const int pieceIndex) const
     res.reserve(static_cast<decltype(res)::size_type>(files.size()));
     for (const lt::file_slice &fileSlice : files)
     {
-        const int index = m_nativeIndexes.indexOf(fileSlice.file_index);
+        const qsizetype index = m_nativeIndexes.indexOf(fileSlice.file_index);
         if (index >= 0)
             res.append(index);
     }
diff --git a/src/base/http/requestparser.cpp b/src/base/http/requestparser.cpp
index 524b39e1f..bfeac9320 100644
--- a/src/base/http/requestparser.cpp
+++ b/src/base/http/requestparser.cpp
@@ -73,7 +73,7 @@ namespace
     std::optional<QStringPair> parseHeaderLine(const QByteArrayView line)
     {
         // [rfc7230] 3.2. Header Fields
-        const int i = line.indexOf(u':');
+        const qsizetype i = line.indexOf(u':');
         if (i <= 0)
         {
             qWarning() << Q_FUNC_INFO << "invalid http header:" << line;
@@ -95,7 +95,7 @@ RequestParser::ParseResult RequestParser::parse(const QByteArray &data)
 RequestParser::ParseResult RequestParser::doParse(const QByteArrayView data)
 {
     // we don't handle malformed requests which use double `LF` as delimiter
-    const int headerEnd = data.indexOf(EOH);
+    const qsizetype headerEnd = data.indexOf(EOH);
     if (headerEnd < 0)
     {
         qDebug() << Q_FUNC_INFO << "incomplete request";
@@ -109,7 +109,7 @@ RequestParser::ParseResult RequestParser::doParse(const QByteArrayView data)
         return {ParseStatus::BadRequest, Request(), 0};
     }
 
-    const int headerLength = headerEnd + EOH.length();
+    const qsizetype headerLength = headerEnd + EOH.length();
 
     // handle supported methods
     if ((m_request.method == HEADER_REQUEST_METHOD_GET) || (m_request.method == HEADER_REQUEST_METHOD_HEAD))
@@ -127,7 +127,7 @@ RequestParser::ParseResult RequestParser::doParse(const QByteArrayView data)
             return Utils::String::parseInt(rawValue).value_or(-1);
         };
 
-        const int contentLength = parseContentLength();
+        const qsizetype contentLength = parseContentLength();
         if (contentLength < 0)
         {
             qWarning() << Q_FUNC_INFO << "bad request: content-length invalid";
@@ -289,7 +289,7 @@ bool RequestParser::parsePostMessage(const QByteArrayView data)
 
         // find boundary delimiter
         const QString boundaryFieldName = u"boundary="_s;
-        const int idx = contentType.indexOf(boundaryFieldName);
+        const qsizetype idx = contentType.indexOf(boundaryFieldName);
         if (idx < 0)
         {
             qWarning() << Q_FUNC_INFO << "Could not find boundary in multipart/form-data header!";
@@ -328,7 +328,7 @@ bool RequestParser::parsePostMessage(const QByteArrayView data)
 
 bool RequestParser::parseFormData(const QByteArrayView data)
 {
-    const int eohPos = data.indexOf(EOH);
+    const qsizetype eohPos = data.indexOf(EOH);
 
     if (eohPos < 0)
     {
@@ -356,7 +356,7 @@ bool RequestParser::parseFormData(const QByteArrayView data)
 
             for (const auto &directive : directives)
             {
-                const int idx = directive.indexOf(u'=');
+                const qsizetype idx = directive.indexOf(u'=');
                 if (idx < 0)
                     continue;
 
diff --git a/src/base/http/requestparser.h b/src/base/http/requestparser.h
index fa8661e1d..850c1e86c 100644
--- a/src/base/http/requestparser.h
+++ b/src/base/http/requestparser.h
@@ -50,7 +50,7 @@ namespace Http
             // when `status != ParseStatus::OK`, `request` & `frameSize` are undefined
             ParseStatus status = ParseStatus::BadRequest;
             Request request;
-            long frameSize = 0;  // http request frame size (bytes)
+            qsizetype frameSize = 0;  // http request frame size (bytes)
         };
 
         static ParseResult parse(const QByteArray &data);
diff --git a/src/base/http/responsegenerator.cpp b/src/base/http/responsegenerator.cpp
index b34b973db..0c4495b93 100644
--- a/src/base/http/responsegenerator.cpp
+++ b/src/base/http/responsegenerator.cpp
@@ -87,7 +87,7 @@ void Http::compressContent(Response &response)
     response.headers.remove(HEADER_CONTENT_ENCODING);
 
     // for very small files, compressing them only wastes cpu cycles
-    const int contentSize = response.content.size();
+    const qsizetype contentSize = response.content.size();
     if (contentSize <= 1024)  // 1 kb
         return;
 
diff --git a/src/base/net/geoipdatabase.cpp b/src/base/net/geoipdatabase.cpp
index 5655827ea..abc358b2b 100644
--- a/src/base/net/geoipdatabase.cpp
+++ b/src/base/net/geoipdatabase.cpp
@@ -305,7 +305,7 @@ QVariantHash GeoIPDatabase::readMetadata() const
     }
 
     const QByteArray data = QByteArray::fromRawData(ptr, size);
-    int index = data.lastIndexOf(METADATA_BEGIN_MARK);
+    qsizetype index = data.lastIndexOf(METADATA_BEGIN_MARK);
     if (index >= 0)
     {
         if (m_size > MAX_METADATA_SIZE)
diff --git a/src/base/net/smtp.cpp b/src/base/net/smtp.cpp
index e130f6b11..851c91100 100644
--- a/src/base/net/smtp.cpp
+++ b/src/base/net/smtp.cpp
@@ -67,7 +67,7 @@ namespace
         // ascii characters 0x36 ("6") and 0x5c ("\") are selected because they have large
         // Hamming distance (http://en.wikipedia.org/wiki/Hamming_distance)
 
-        for (int i = 0; i < key.length(); ++i)
+        for (qsizetype i = 0; i < key.length(); ++i)
         {
             innerPadding[i] = innerPadding[i] ^ key.at(i); // XOR operation between every byte in key and innerpadding, of key length
             outerPadding[i] = outerPadding[i] ^ key.at(i); // XOR operation between every byte in key and outerpadding, of key length
@@ -148,7 +148,7 @@ void Smtp::sendMail(const QString &from, const QString &to, const QString &subje
     // Encode the body in base64
     QString crlfBody = body;
     const QByteArray b = crlfBody.replace(u"\n"_s, u"\r\n"_s).toUtf8().toBase64();
-    for (int i = 0, end = b.length(); i < end; i += 78)
+    for (qsizetype i = 0, end = b.length(); i < end; i += 78)
         m_message += b.mid(i, 78);
     m_from = from;
     m_rcpt = to;
@@ -187,7 +187,7 @@ void Smtp::readyRead()
     m_buffer += m_socket->readAll();
     while (true)
     {
-        const int pos = m_buffer.indexOf("\r\n");
+        const qsizetype pos = m_buffer.indexOf("\r\n");
         if (pos < 0) return; // Loop exit condition
         const QByteArray line = m_buffer.first(pos);
 #if QT_VERSION >= QT_VERSION_CHECK(6, 8, 0)
@@ -347,7 +347,7 @@ QByteArray Smtp::encodeMimeHeader(const QString &key, const QString &value, cons
         const QByteArray utf8 = value.toUtf8();
         // Use base64 encoding
         const QByteArray base64 = utf8.toBase64();
-        const int ct = base64.length();
+        const qsizetype ct = base64.length();
         line += "=?utf-8?b?";
         for (int i = 0; i < ct; i += 4)
         {
diff --git a/src/base/path.cpp b/src/base/path.cpp
index 55162d6df..262caf026 100644
--- a/src/base/path.cpp
+++ b/src/base/path.cpp
@@ -143,7 +143,7 @@ Path Path::rootItem() const
 {
     // does not support UNC path
 
-    const int slashIndex = m_pathStr.indexOf(u'/');
+    const qsizetype slashIndex = m_pathStr.indexOf(u'/');
     if (slashIndex < 0)
         return *this;
 
@@ -162,7 +162,7 @@ Path Path::parentPath() const
 {
     // does not support UNC path
 
-    const int slashIndex = m_pathStr.lastIndexOf(u'/');
+    const qsizetype slashIndex = m_pathStr.lastIndexOf(u'/');
     if (slashIndex == -1)
         return {};
 
@@ -180,7 +180,7 @@ Path Path::parentPath() const
 
 QString Path::filename() const
 {
-    const int slashIndex = m_pathStr.lastIndexOf(u'/');
+    const qsizetype slashIndex = m_pathStr.lastIndexOf(u'/');
     if (slashIndex == -1)
         return m_pathStr;
 
@@ -193,9 +193,9 @@ QString Path::extension() const
     if (!suffix.isEmpty())
         return (u"." + suffix);
 
-    const int slashIndex = m_pathStr.lastIndexOf(u'/');
+    const qsizetype slashIndex = m_pathStr.lastIndexOf(u'/');
     const auto filename = QStringView(m_pathStr).sliced(slashIndex + 1);
-    const int dotIndex = filename.lastIndexOf(u'.', -2);
+    const qsizetype dotIndex = filename.lastIndexOf(u'.', -2);
     return ((dotIndex == -1) ? QString() : filename.sliced(dotIndex).toString());
 }
 
diff --git a/src/base/rss/feed_serializer.cpp b/src/base/rss/feed_serializer.cpp
index 838ad06a9..e55b7dc14 100644
--- a/src/base/rss/feed_serializer.cpp
+++ b/src/base/rss/feed_serializer.cpp
@@ -101,7 +101,7 @@ QList<QVariantHash> RSS::Private::FeedSerializer::loadArticles(const QByteArray
     QList<QVariantHash> result;
     const QJsonArray jsonArr = jsonDoc.array();
     result.reserve(jsonArr.size());
-    for (int i = 0; i < jsonArr.size(); ++i)
+    for (qsizetype i = 0; i < jsonArr.size(); ++i)
     {
         const QJsonValue jsonVal = jsonArr[i];
         if (!jsonVal.isObject())
diff --git a/src/base/rss/rss_autodownloader.cpp b/src/base/rss/rss_autodownloader.cpp
index 873223dbd..c77b1d9bd 100644
--- a/src/base/rss/rss_autodownloader.cpp
+++ b/src/base/rss/rss_autodownloader.cpp
@@ -406,7 +406,7 @@ void AutoDownloader::handleFeedURLChanged(Feed *feed, const QString &oldURL)
 {
     for (AutoDownloadRule &rule : m_rules)
     {
-        if (const auto i = rule.feedURLs().indexOf(oldURL); i >= 0)
+        if (const qsizetype i = rule.feedURLs().indexOf(oldURL); i >= 0)
         {
             auto feedURLs = rule.feedURLs();
             feedURLs.replace(i, feed->url());
diff --git a/src/base/rss/rss_folder.cpp b/src/base/rss/rss_folder.cpp
index ccf06e0ef..62dc8bb6e 100644
--- a/src/base/rss/rss_folder.cpp
+++ b/src/base/rss/rss_folder.cpp
@@ -60,7 +60,7 @@ QList<Article *> Folder::articles() const
 
     for (Item *item : asConst(items()))
     {
-        int n = news.size();
+        qsizetype n = news.size();
         news << item->articles();
         std::inplace_merge(news.begin(), news.begin() + n, news.end()
                            , [](Article *a1, Article *a2)
diff --git a/src/base/rss/rss_item.cpp b/src/base/rss/rss_item.cpp
index 19f340fa0..11ced1479 100644
--- a/src/base/rss/rss_item.cpp
+++ b/src/base/rss/rss_item.cpp
@@ -94,7 +94,7 @@ QStringList Item::expandPath(const QString &path)
     //    if (!isValidRSSFolderName(folder))
     //        return result;
 
-    int index = 0;
+    qsizetype index = 0;
     while ((index = path.indexOf(Item::PathSeparator, index)) >= 0)
     {
         result << path.first(index);
@@ -107,12 +107,12 @@ QStringList Item::expandPath(const QString &path)
 
 QString Item::parentPath(const QString &path)
 {
-    const int pos = path.lastIndexOf(Item::PathSeparator);
+    const qsizetype pos = path.lastIndexOf(Item::PathSeparator);
     return (pos >= 0) ? path.first(pos) : QString();
 }
 
 QString Item::relativeName(const QString &path)
 {
-    const int pos = path.lastIndexOf(Item::PathSeparator);
+    const qsizetype pos = path.lastIndexOf(Item::PathSeparator);
     return (pos >= 0) ? path.sliced(pos + 1) : path;
 }
diff --git a/src/base/rss/rss_parser.cpp b/src/base/rss/rss_parser.cpp
index d34212b40..2ccb833b3 100644
--- a/src/base/rss/rss_parser.cpp
+++ b/src/base/rss/rss_parser.cpp
@@ -452,7 +452,7 @@ namespace
         //       if (month >= 12 || dayOfWeek >= 7
         //       ||  (dayOfWeek < 0  &&  format == RFCDateDay))
         //         return QDateTime;
-        const int i = parts[nyear].size();
+        const qsizetype i = parts[nyear].size();
         if (i < 4)
         {
             // It's an obsolete year specification with less than 4 digits
@@ -503,7 +503,7 @@ namespace
                     {
                         // Check for any other alphabetic time zone
                         bool nonalpha = false;
-                        for (int i = 0, end = zone.size(); (i < end) && !nonalpha; ++i)
+                        for (qsizetype i = 0, end = zone.size(); (i < end) && !nonalpha; ++i)
                             nonalpha = !isalpha(zone[i]);
                         if (nonalpha)
                             return {};
diff --git a/src/base/search/searchhandler.cpp b/src/base/search/searchhandler.cpp
index 670c2b42a..8527cdb49 100644
--- a/src/base/search/searchhandler.cpp
+++ b/src/base/search/searchhandler.cpp
@@ -206,7 +206,7 @@ void SearchHandler::readSearchOutput()
 bool SearchHandler::parseSearchResult(const QByteArrayView line, SearchResult &searchResult)
 {
     const QList<QByteArrayView> parts = Utils::ByteArray::splitToViews(line, "|");
-    const int nbFields = parts.size();
+    const qsizetype nbFields = parts.size();
 
     if (nbFields <= PL_ENGINE_URL)
         return false; // Anything after ENGINE_URL is optional
diff --git a/src/base/settingsstorage.cpp b/src/base/settingsstorage.cpp
index c6006beb7..26d421176 100644
--- a/src/base/settingsstorage.cpp
+++ b/src/base/settingsstorage.cpp
@@ -148,7 +148,7 @@ void SettingsStorage::readNativeSettings()
                .arg(newPath.toString()), Log::WARNING);
 
         QString finalPathStr = newPath.data();
-        const int index = finalPathStr.lastIndexOf(u"_new", -1, Qt::CaseInsensitive);
+        const qsizetype index = finalPathStr.lastIndexOf(u"_new", -1, Qt::CaseInsensitive);
         finalPathStr.remove(index, 4);
 
         const Path finalPath {finalPathStr};
@@ -201,7 +201,7 @@ bool SettingsStorage::writeNativeSettings() const
     }
 
     QString finalPathStr = newPath.data();
-    const int index = finalPathStr.lastIndexOf(u"_new", -1, Qt::CaseInsensitive);
+    const qsizetype index = finalPathStr.lastIndexOf(u"_new", -1, Qt::CaseInsensitive);
     finalPathStr.remove(index, 4);
 
     const Path finalPath {finalPathStr};
diff --git a/src/base/utils/compare.cpp b/src/base/utils/compare.cpp
index 15d438b2d..0ebc52ff8 100644
--- a/src/base/utils/compare.cpp
+++ b/src/base/utils/compare.cpp
@@ -74,7 +74,7 @@ int Utils::Compare::naturalCompare(const QString &left, const QString &right, co
                 return (numViewL.length() - numViewR.length());
 
             // both string/view has the same length
-            for (int i = 0; i < numViewL.length(); ++i)
+            for (qsizetype i = 0; i < numViewL.length(); ++i)
             {
                 const QChar numL = numViewL[i];
                 const QChar numR = numViewR[i];
diff --git a/src/base/utils/foreignapps.cpp b/src/base/utils/foreignapps.cpp
index 91a254d91..5b834ffbc 100644
--- a/src/base/utils/foreignapps.cpp
+++ b/src/base/utils/foreignapps.cpp
@@ -82,7 +82,7 @@ namespace
             // User reports: `python --version` -> "Python 3.6.6+"
             // So trim off unrelated characters
             const auto versionStr = QString::fromLocal8Bit(outputSplit[1]);
-            const int idx = versionStr.indexOf(QRegularExpression(u"[^\\.\\d]"_s));
+            const qsizetype idx = versionStr.indexOf(QRegularExpression(u"[^\\.\\d]"_s));
             const auto version = PythonInfo::Version::fromString(versionStr.left(idx));
             if (!version.isValid())
                 return false;
diff --git a/src/base/utils/password.cpp b/src/base/utils/password.cpp
index fd3ffdfee..75019d9cc 100644
--- a/src/base/utils/password.cpp
+++ b/src/base/utils/password.cpp
@@ -57,11 +57,11 @@ namespace Utils
 // Taken from https://crackstation.net/hashing-security.htm
 bool Utils::Password::slowEquals(const QByteArray &a, const QByteArray &b)
 {
-    const int lengthA = a.length();
-    const int lengthB = b.length();
+    const qsizetype lengthA = a.length();
+    const qsizetype lengthB = b.length();
 
-    int diff = lengthA ^ lengthB;
-    for (int i = 0; (i < lengthA) && (i < lengthB); ++i)
+    qsizetype diff = lengthA ^ lengthB;
+    for (qsizetype i = 0; (i < lengthA) && (i < lengthB); ++i)
         diff |= a[i] ^ b[i];
 
     return (diff == 0);
diff --git a/src/base/utils/version.h b/src/base/utils/version.h
index 36f20512e..a01688380 100644
--- a/src/base/utils/version.h
+++ b/src/base/utils/version.h
@@ -140,7 +140,7 @@ namespace Utils
         static Version fromString(const QStringView string, const Version &defaultVersion = {})
         {
             const QList<QStringView> stringParts = string.split(u'.');
-            const int count = stringParts.size();
+            const qsizetype count = stringParts.size();
 
             if ((count > N) || (count < Mandatory))
                 return defaultVersion;
diff --git a/src/gui/addnewtorrentdialog.cpp b/src/gui/addnewtorrentdialog.cpp
index a82dabf52..5ab0fd0d0 100644
--- a/src/gui/addnewtorrentdialog.cpp
+++ b/src/gui/addnewtorrentdialog.cpp
@@ -87,7 +87,7 @@ namespace
     // savePath is a folder, not an absolute file path
     int indexOfPath(const FileSystemPathComboEdit *fsPathEdit, const Path &savePath)
     {
-        for (int i = 0; i < fsPathEdit->count(); ++i)
+        for (qsizetype i = 0; i < fsPathEdit->count(); ++i)
         {
             if (fsPathEdit->item(i) == savePath)
                 return i;
@@ -130,7 +130,7 @@ namespace
 
         auto pathList = settings()->loadValue<QStringList>(settingsKey);
 
-        const int selectedSavePathIndex = pathList.indexOf(path.toString());
+        const qsizetype selectedSavePathIndex = pathList.indexOf(path.toString());
         if (selectedSavePathIndex > -1)
             pathList.move(selectedSavePathIndex, 0);
         else
@@ -598,7 +598,7 @@ void AddNewTorrentDialog::updateDiskSpaceLabel()
         const auto torrentInfo = *torrentDescr.info();
         const QList<BitTorrent::DownloadPriority> &priorities = m_contentAdaptor->filePriorities();
         Q_ASSERT(priorities.size() == torrentInfo.filesCount());
-        for (int i = 0; i < priorities.size(); ++i)
+        for (qsizetype i = 0; i < priorities.size(); ++i)
         {
             if (priorities[i] > BitTorrent::DownloadPriority::Ignored)
                 torrentSize += torrentInfo.fileSize(i);
diff --git a/src/gui/fspathedit.cpp b/src/gui/fspathedit.cpp
index 477a93a77..a9f6c64a6 100644
--- a/src/gui/fspathedit.cpp
+++ b/src/gui/fspathedit.cpp
@@ -230,8 +230,8 @@ void FileSystemPathEdit::setFileNameFilter(const QString &val)
     // QFileSystemModel applies name filters to directories too.
     // To use the filters we have to subclass QFileSystemModel and skip directories while filtering
     // extract file masks
-    const int openBracePos = val.indexOf(u'(');
-    const int closeBracePos = val.indexOf(u')', (openBracePos + 1));
+    const qsizetype openBracePos = val.indexOf(u'(');
+    const qsizetype closeBracePos = val.indexOf(u')', (openBracePos + 1));
     if ((openBracePos > 0) && (closeBracePos > 0) && (closeBracePos > openBracePos + 2))
     {
         const QString filterString = val.sliced((openBracePos + 1), (closeBracePos - openBracePos - 1));
diff --git a/src/gui/optionsdialog.cpp b/src/gui/optionsdialog.cpp
index 56bf1a457..f5d597232 100644
--- a/src/gui/optionsdialog.cpp
+++ b/src/gui/optionsdialog.cpp
@@ -1874,7 +1874,7 @@ void OptionsDialog::setLocale(const QString &localeStr)
     if (index < 0)
     {
         //Attempt to find a language match without a country
-        const int pos = name.indexOf(u'_');
+        const qsizetype pos = name.indexOf(u'_');
         if (pos > -1)
         {
             const QString lang = name.first(pos);
diff --git a/src/gui/properties/downloadedpiecesbar.cpp b/src/gui/properties/downloadedpiecesbar.cpp
index 305baad9f..7c6d51cf5 100644
--- a/src/gui/properties/downloadedpiecesbar.cpp
+++ b/src/gui/properties/downloadedpiecesbar.cpp
@@ -154,7 +154,7 @@ QImage DownloadedPiecesBar::renderImage()
     QList<float> scaledPiecesDl = bitfieldToFloatVector(m_downloadedPieces, image.width());
 
     // filling image
-    for (int x = 0; x < scaledPieces.size(); ++x)
+    for (qsizetype x = 0; x < scaledPieces.size(); ++x)
     {
         float piecesToValue = scaledPieces.at(x);
         float piecesToValueDl = scaledPiecesDl.at(x);
diff --git a/src/gui/properties/pieceavailabilitybar.cpp b/src/gui/properties/pieceavailabilitybar.cpp
index 5a9e61845..0e9e2a656 100644
--- a/src/gui/properties/pieceavailabilitybar.cpp
+++ b/src/gui/properties/pieceavailabilitybar.cpp
@@ -145,7 +145,7 @@ QImage PieceAvailabilityBar::renderImage()
     QList<float> scaledPieces = intToFloatVector(m_pieces, image.width());
 
     // filling image
-    for (int x = 0; x < scaledPieces.size(); ++x)
+    for (qsizetype x = 0; x < scaledPieces.size(); ++x)
     {
         float piecesToValue = scaledPieces.at(x);
         image.setPixel(x, 0, pieceColors()[piecesToValue * 255]);
diff --git a/src/gui/torrentcategorydialog.cpp b/src/gui/torrentcategorydialog.cpp
index a9762d81d..ce02d6667 100644
--- a/src/gui/torrentcategorydialog.cpp
+++ b/src/gui/torrentcategorydialog.cpp
@@ -136,7 +136,7 @@ void TorrentCategoryDialog::setCategoryName(const QString &categoryName)
 {
     m_ui->textCategoryName->setText(categoryName);
 
-    const int subcategoryNameStart = categoryName.lastIndexOf(u"/") + 1;
+    const qsizetype subcategoryNameStart = categoryName.lastIndexOf(u'/') + 1;
     m_ui->textCategoryName->setSelection(subcategoryNameStart, (categoryName.size() - subcategoryNameStart));
 }
 
diff --git a/src/gui/torrentcontentmodel.cpp b/src/gui/torrentcontentmodel.cpp
index 73aa8f766..0238174c3 100644
--- a/src/gui/torrentcontentmodel.cpp
+++ b/src/gui/torrentcontentmodel.cpp
@@ -194,7 +194,7 @@ void TorrentContentModel::updateFilesProgress()
     if (m_filesIndex.size() != filesProgress.size()) [[unlikely]]
         return;
 
-    for (int i = 0; i < filesProgress.size(); ++i)
+    for (qsizetype i = 0; i < filesProgress.size(); ++i)
         m_filesIndex[i]->setProgress(filesProgress[i]);
     // Update folders progress in the tree
     m_rootItem->recalculateProgress();
@@ -211,7 +211,7 @@ void TorrentContentModel::updateFilesPriorities()
     if (m_filesIndex.size() != fprio.size())
         return;
 
-    for (int i = 0; i < fprio.size(); ++i)
+    for (qsizetype i = 0; i < fprio.size(); ++i)
         m_filesIndex[i]->setPriority(static_cast<BitTorrent::DownloadPriority>(fprio[i]));
 }
 
@@ -226,7 +226,7 @@ void TorrentContentModel::updateFilesAvailability()
         if (!m_contentHandler || (m_contentHandler != handler))
             return;
 
-        for (int i = 0; i < m_filesIndex.size(); ++i)
+        for (qsizetype i = 0; i < m_filesIndex.size(); ++i)
             m_filesIndex[i]->setAvailability(availableFileFractions.value(i, 0));
         // Update folders progress in the tree
         m_rootItem->recalculateProgress();
diff --git a/src/gui/torrentcontentmodelfolder.cpp b/src/gui/torrentcontentmodelfolder.cpp
index baaa098aa..418e36306 100644
--- a/src/gui/torrentcontentmodelfolder.cpp
+++ b/src/gui/torrentcontentmodelfolder.cpp
@@ -98,7 +98,7 @@ void TorrentContentModelFolder::updatePriority()
     // then the folder should have the same
     // priority
     const BitTorrent::DownloadPriority prio = m_childItems.constFirst()->priority();
-    for (int i = 1; i < m_childItems.size(); ++i)
+    for (qsizetype i = 1; i < m_childItems.size(); ++i)
     {
         if (m_childItems.at(i)->priority() != prio)
         {
diff --git a/src/gui/transferlistfilters/categoryfiltermodel.cpp b/src/gui/transferlistfilters/categoryfiltermodel.cpp
index 45516321f..4f27dd640 100644
--- a/src/gui/transferlistfilters/categoryfiltermodel.cpp
+++ b/src/gui/transferlistfilters/categoryfiltermodel.cpp
@@ -100,12 +100,12 @@ public:
             m_parent->decreaseTorrentsCount(delta);
     }
 
-    int pos() const
+    qsizetype pos() const
     {
         if (!m_parent)
             return -1;
 
-        if (const int posByName = m_parent->m_childUids.indexOf(m_name); posByName >= 0)
+        if (const qsizetype posByName = m_parent->m_childUids.indexOf(m_name); posByName >= 0)
             return posByName;
 
         // special cases
@@ -174,7 +174,7 @@ namespace
 {
     QString shortName(const QString &fullName)
     {
-        const int pos = fullName.lastIndexOf(u'/');
+        const qsizetype pos = fullName.lastIndexOf(u'/');
         if (pos >= 0)
             return fullName.sliced(pos + 1);
         return fullName;
diff --git a/src/gui/transferlistfilters/tagfiltermodel.cpp b/src/gui/transferlistfilters/tagfiltermodel.cpp
index da76e7be6..6e741cf86 100644
--- a/src/gui/transferlistfilters/tagfiltermodel.cpp
+++ b/src/gui/transferlistfilters/tagfiltermodel.cpp
@@ -322,7 +322,7 @@ int TagFilterModel::findRow(const Tag &tag) const
     if (!tag.isValid())
         return -1;
 
-    for (int i = 0; i < m_tagItems.size(); ++i)
+    for (qsizetype i = 0; i < m_tagItems.size(); ++i)
     {
         if (m_tagItems[i].tag() == tag)
             return i;
diff --git a/src/gui/watchedfoldersmodel.cpp b/src/gui/watchedfoldersmodel.cpp
index 0bb4e4c75..344f1b9ac 100644
--- a/src/gui/watchedfoldersmodel.cpp
+++ b/src/gui/watchedfoldersmodel.cpp
@@ -172,7 +172,7 @@ void WatchedFoldersModel::onFolderSet(const Path &path, const TorrentFilesWatche
 
 void WatchedFoldersModel::onFolderRemoved(const Path &path)
 {
-    const int row = m_watchedFolders.indexOf(path);
+    const qsizetype row = m_watchedFolders.indexOf(path);
     if (row >= 0)
         removeRows(row, 1);
 
diff --git a/src/webui/api/searchcontroller.cpp b/src/webui/api/searchcontroller.cpp
index 0257b16ec..c7baca6d8 100644
--- a/src/webui/api/searchcontroller.cpp
+++ b/src/webui/api/searchcontroller.cpp
@@ -184,7 +184,7 @@ void SearchController::resultsAction()
 
     const std::shared_ptr<SearchHandler> &searchHandler = iter.value();
     const QList<SearchResult> searchResults = searchHandler->results();
-    const int size = searchResults.size();
+    const qsizetype size = searchResults.size();
 
     if (offset > size)
         throw APIError(APIErrorType::Conflict, tr("Offset is out of range"));
diff --git a/src/webui/api/torrentscontroller.cpp b/src/webui/api/torrentscontroller.cpp
index 10b7033a4..550eb3ec9 100644
--- a/src/webui/api/torrentscontroller.cpp
+++ b/src/webui/api/torrentscontroller.cpp
@@ -637,7 +637,7 @@ void TorrentsController::infoAction()
         });
     }
 
-    const int size = torrentList.size();
+    const qsizetype size = torrentList.size();
     // normalize offset
     if (offset < 0)
         offset = size + offset;
@@ -993,11 +993,11 @@ void TorrentsController::pieceStatesAction()
 
     QJsonArray pieceStates;
     const QBitArray states = torrent->pieces();
-    for (int i = 0; i < states.size(); ++i)
+    for (qsizetype i = 0; i < states.size(); ++i)
         pieceStates.append(static_cast<int>(states[i]) * 2);
 
     const QBitArray dlstates = torrent->fetchDownloadingPieces().takeResult();
-    for (int i = 0; i < states.size(); ++i)
+    for (qsizetype i = 0; i < states.size(); ++i)
     {
         if (dlstates[i])
             pieceStates[i] = 1;
diff --git a/src/webui/webapplication.cpp b/src/webui/webapplication.cpp
index e7bd3d02f..35cba850e 100644
--- a/src/webui/webapplication.cpp
+++ b/src/webui/webapplication.cpp
@@ -88,7 +88,7 @@ namespace
 
         for (const auto &cookie : cookies)
         {
-            const int idx = cookie.indexOf(u'=');
+            const qsizetype idx = cookie.indexOf(u'=');
             if (idx < 0)
                 continue;
 
@@ -230,9 +230,9 @@ void WebApplication::translateDocument(QString &data) const
 {
     const QRegularExpression regex(u"QBT_TR\\((([^\\)]|\\)(?!QBT_TR))+)\\)QBT_TR\\[CONTEXT=([a-zA-Z_][a-zA-Z0-9_]*)\\]"_s);
 
-    int i = 0;
+    qsizetype i = 0;
     bool found = true;
-    while (i < data.size() && found)
+    while ((i < data.size()) && found)
     {
         QRegularExpressionMatch regexMatch;
         i = data.indexOf(regex, i, &regexMatch);
@@ -483,7 +483,7 @@ void WebApplication::configure()
 
         for (const QStringView line : customHeaderLines)
         {
-            const int idx = line.indexOf(u':');
+            const qsizetype idx = line.indexOf(u':');
             if (idx < 0)
             {
                 // require separator `:` to be present even if `value` field can be empty