diff --git a/src/cli/commandlineparser.cpp b/src/cli/commandlineparser.cpp
index 8c5ef697..1dfb3866 100644
--- a/src/cli/commandlineparser.cpp
+++ b/src/cli/commandlineparser.cpp
@@ -209,8 +209,8 @@ bool CommandLineParser::parse(const QStringList& args)
     ok = processIfOptionIsHelp(args, it, actualNode);
     // process the other args
     for (; it != args.cend() && ok; ++it) {
-        const QString& value = *it;
-        if (value.startsWith(QLatin1String("-"))) {
+        const QString& val = *it;
+        if (val.startsWith(QLatin1String("-"))) {
             ok = processOptions(args, it, actualNode);
 
         } else {
diff --git a/src/config/cacheutils.cpp b/src/config/cacheutils.cpp
index b84ead9c..a5a60efe 100644
--- a/src/config/cacheutils.cpp
+++ b/src/config/cacheutils.cpp
@@ -46,4 +46,4 @@ QRect getLastRegion()
     }
 
     return lastRegion;
-}
\ No newline at end of file
+}
diff --git a/src/config/cacheutils.h b/src/config/cacheutils.h
index ad82ca4a..96413a23 100644
--- a/src/config/cacheutils.h
+++ b/src/config/cacheutils.h
@@ -11,4 +11,4 @@ QString getCachePath();
 QRect getLastRegion();
 void setLastRegion(QRect const& newRegion);
 
-#endif // FLAMESHOT_CACHEUTILS_H
\ No newline at end of file
+#endif // FLAMESHOT_CACHEUTILS_H
diff --git a/src/config/clickablelabel.cpp b/src/config/clickablelabel.cpp
index c8dca6d9..be827647 100644
--- a/src/config/clickablelabel.cpp
+++ b/src/config/clickablelabel.cpp
@@ -7,7 +7,7 @@ ClickableLabel::ClickableLabel(QWidget* parent)
   : QLabel(parent)
 {}
 
-ClickableLabel::ClickableLabel(QString s, QWidget* parent)
+ClickableLabel::ClickableLabel(const QString& s, QWidget* parent)
   : QLabel(parent)
 {
     setText(s);
diff --git a/src/config/clickablelabel.h b/src/config/clickablelabel.h
index 068de199..c5e6f332 100644
--- a/src/config/clickablelabel.h
+++ b/src/config/clickablelabel.h
@@ -10,7 +10,7 @@ class ClickableLabel : public QLabel
     Q_OBJECT
 public:
     explicit ClickableLabel(QWidget* parent = nullptr);
-    ClickableLabel(QString s, QWidget* parent = nullptr);
+    ClickableLabel(const QString& s, QWidget* parent = nullptr);
 
 signals:
     void clicked();
diff --git a/src/config/filenameeditor.cpp b/src/config/filenameeditor.cpp
index 3f0f62d6..027b04ef 100644
--- a/src/config/filenameeditor.cpp
+++ b/src/config/filenameeditor.cpp
@@ -106,7 +106,7 @@ void FileNameEditor::resetName()
     m_nameEditor->setText(ConfigHandler().filenamePattern());
 }
 
-void FileNameEditor::addToNameEditor(QString s)
+void FileNameEditor::addToNameEditor(const QString& s)
 {
     m_nameEditor->setText(m_nameEditor->text() + s);
     m_nameEditor->setFocus();
diff --git a/src/config/filenameeditor.h b/src/config/filenameeditor.h
index 99b4be2f..04697ab4 100644
--- a/src/config/filenameeditor.h
+++ b/src/config/filenameeditor.h
@@ -32,7 +32,7 @@ private:
     void initWidgets();
 
 public slots:
-    void addToNameEditor(QString s);
+    void addToNameEditor(const QString& s);
     void updateComponents();
 
 private slots:
diff --git a/src/config/generalconf.cpp b/src/config/generalconf.cpp
index fa679691..6205c6b5 100644
--- a/src/config/generalconf.cpp
+++ b/src/config/generalconf.cpp
@@ -486,9 +486,9 @@ void GeneralConf::initSaveAfterCopy()
     m_screenshotPathFixedCheck =
       new QCheckBox(tr("Use fixed path for screenshots to save"), this);
     connect(m_screenshotPathFixedCheck,
-            SIGNAL(toggled(bool)),
+            &QCheckBox::toggled,
             this,
-            SLOT(togglePathFixed()));
+            &GeneralConf::togglePathFixed);
 
     vboxLayout->addLayout(pathLayout);
     vboxLayout->addWidget(m_screenshotPathFixedCheck);
@@ -510,9 +510,9 @@ void GeneralConf::initSaveAfterCopy()
     m_setSaveAsFileExtension->setCurrentIndex(currentIndex);
 
     connect(m_setSaveAsFileExtension,
-            SIGNAL(currentTextChanged(QString)),
+            &QComboBox::currentTextChanged,
             this,
-            SLOT(setSaveAsFileExtension(QString)));
+            &GeneralConf::setSaveAsFileExtension);
 
     extensionLayout->addWidget(m_setSaveAsFileExtension);
     vboxLayout->addLayout(extensionLayout);
@@ -539,9 +539,9 @@ void GeneralConf::initUploadHistoryMax()
       QStringLiteral("color: %1").arg(foreground));
 
     connect(m_uploadHistoryMax,
-            SIGNAL(valueChanged(int)),
+            static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
             this,
-            SLOT(uploadHistoryMaxChanged(int)));
+            &GeneralConf::uploadHistoryMaxChanged);
     vboxLayout->addWidget(m_uploadHistoryMax);
 }
 
@@ -560,9 +560,9 @@ void GeneralConf::initUploadClientSecret()
       QStringLiteral("color: %1").arg(foreground));
     m_uploadClientKey->setText(ConfigHandler().uploadClientSecret());
     connect(m_uploadClientKey,
-            SIGNAL(editingFinished()),
+            &QLineEdit::editingFinished,
             this,
-            SLOT(uploadClientKeyEdited()));
+            &GeneralConf::uploadClientKeyEdited);
     vboxLayout->addWidget(m_uploadClientKey);
 }
 
@@ -591,7 +591,10 @@ void GeneralConf::initUndoLimit()
     QString foreground = this->palette().windowText().color().name();
     m_undoLimit->setStyleSheet(QStringLiteral("color: %1").arg(foreground));
 
-    connect(m_undoLimit, SIGNAL(valueChanged(int)), this, SLOT(undoLimit(int)));
+    connect(m_undoLimit,
+            static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
+            this,
+            &GeneralConf::undoLimit);
 
     vboxLayout->addWidget(m_undoLimit);
 }
@@ -670,7 +673,7 @@ void GeneralConf::initUploadWithoutConfirmation()
     });
 }
 
-const QString GeneralConf::chooseFolder(const QString pathDefault)
+const QString GeneralConf::chooseFolder(const QString& pathDefault)
 {
     QString path;
     if (pathDefault.isEmpty()) {
@@ -685,13 +688,13 @@ const QString GeneralConf::chooseFolder(const QString pathDefault)
     if (path.isEmpty()) {
         return path;
     }
-    if (!path.isEmpty()) {
-        if (!QFileInfo(path).isWritable()) {
-            QMessageBox::about(
-              this, tr("Error"), tr("Unable to write to directory."));
-            return QString();
-        }
+
+    if (!QFileInfo(path).isWritable()) {
+        QMessageBox::about(
+          this, tr("Error"), tr("Unable to write to directory."));
+        return QString();
     }
+
     return path;
 }
 
@@ -733,9 +736,9 @@ void GeneralConf::initShowSelectionGeometry()
 
     m_scrollAreaLayout->addLayout(tobox);
     connect(m_xywhTimeout,
-            SIGNAL(valueChanged(int)),
+            static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
             this,
-            SLOT(setSelGeoHideTime(int)));
+            &GeneralConf::setSelGeoHideTime);
 
     auto* box = new QGroupBox(tr("Selection Geometry Display"));
     box->setFlat(true);
@@ -763,10 +766,11 @@ void GeneralConf::initShowSelectionGeometry()
     m_selectGeometryLocation->setCurrentIndex(
       m_selectGeometryLocation->findData(pos));
 
-    connect(m_selectGeometryLocation,
-            SIGNAL(currentIndexChanged(int)),
-            this,
-            SLOT(setGeometryLocation(int)));
+    connect(
+      m_selectGeometryLocation,
+      static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
+      this,
+      &GeneralConf::setGeometryLocation);
 
     selGeoLayout->addWidget(m_selectGeometryLocation);
     vboxLayout->addLayout(selGeoLayout);
@@ -789,7 +793,7 @@ void GeneralConf::togglePathFixed()
     ConfigHandler().setSavePathFixed(m_screenshotPathFixedCheck->isChecked());
 }
 
-void GeneralConf::setSaveAsFileExtension(QString extension)
+void GeneralConf::setSaveAsFileExtension(const QString& extension)
 {
     ConfigHandler().setSaveAsFileExtension(extension);
 }
diff --git a/src/config/generalconf.h b/src/config/generalconf.h
index 29bbfffe..0444de7c 100644
--- a/src/config/generalconf.h
+++ b/src/config/generalconf.h
@@ -54,12 +54,12 @@ private slots:
     void togglePathFixed();
     void uploadClientKeyEdited();
     void useJpgForClipboardChanged(bool checked);
-    void setSaveAsFileExtension(QString extension);
+    void setSaveAsFileExtension(const QString& extension);
     void setGeometryLocation(int index);
     void setSelGeoHideTime(int v);
 
 private:
-    const QString chooseFolder(const QString currentPath = "");
+    const QString chooseFolder(const QString& currentPath = "");
 
     void initAllowMultipleGuiInstances();
     void initAntialiasingPinZoom();
diff --git a/src/config/setshortcutwidget.cpp b/src/config/setshortcutwidget.cpp
index c2002406..8c0de2d0 100644
--- a/src/config/setshortcutwidget.cpp
+++ b/src/config/setshortcutwidget.cpp
@@ -9,7 +9,8 @@
 #include <QLayout>
 #include <QPixmap>
 
-SetShortcutDialog::SetShortcutDialog(QDialog* parent, QString shortcutName)
+SetShortcutDialog::SetShortcutDialog(QDialog* parent,
+                                     const QString& shortcutName)
   : QDialog(parent)
 {
     setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
diff --git a/src/config/setshortcutwidget.h b/src/config/setshortcutwidget.h
index 4d25df49..12324613 100644
--- a/src/config/setshortcutwidget.h
+++ b/src/config/setshortcutwidget.h
@@ -15,7 +15,7 @@ class SetShortcutDialog : public QDialog
     Q_OBJECT
 public:
     explicit SetShortcutDialog(QDialog* parent = nullptr,
-                               QString shortcutName = "");
+                               const QString& shortcutName = "");
     const QKeySequence& shortcut();
 
 public:
diff --git a/src/core/flameshot.cpp b/src/core/flameshot.cpp
index ca7d5fb2..54b0ada4 100644
--- a/src/core/flameshot.cpp
+++ b/src/core/flameshot.cpp
@@ -279,8 +279,9 @@ Flameshot::Origin Flameshot::origin()
 bool Flameshot::resolveAnyConfigErrors()
 {
     bool resolved = true;
-    ConfigHandler config;
-    if (!config.checkUnrecognizedSettings() || !config.checkSemantics()) {
+    ConfigHandler confighandler;
+    if (!confighandler.checkUnrecognizedSettings() ||
+        !confighandler.checkSemantics()) {
         auto* resolver = new ConfigResolver();
         QObject::connect(
           resolver, &ConfigResolver::rejected, [resolver, &resolved]() {
@@ -333,7 +334,7 @@ void Flameshot::requestCapture(const CaptureRequest& request)
     }
 }
 
-void Flameshot::exportCapture(QPixmap capture,
+void Flameshot::exportCapture(const QPixmap& capture,
                               QRect& selection,
                               const CaptureRequest& req)
 {
diff --git a/src/core/flameshot.h b/src/core/flameshot.h
index 01f13f8a..f625a801 100644
--- a/src/core/flameshot.h
+++ b/src/core/flameshot.h
@@ -56,7 +56,9 @@ signals:
 
 public slots:
     void requestCapture(const CaptureRequest& request);
-    void exportCapture(QPixmap p, QRect& selection, const CaptureRequest& req);
+    void exportCapture(const QPixmap& p,
+                       QRect& selection,
+                       const CaptureRequest& req);
 
 private:
     Flameshot();
diff --git a/src/core/flameshotdaemon.cpp b/src/core/flameshotdaemon.cpp
index fdad6a20..b8fdf3cd 100644
--- a/src/core/flameshotdaemon.cpp
+++ b/src/core/flameshotdaemon.cpp
@@ -106,7 +106,7 @@ void FlameshotDaemon::start()
     }
 }
 
-void FlameshotDaemon::createPin(QPixmap capture, QRect geometry)
+void FlameshotDaemon::createPin(const QPixmap& capture, QRect geometry)
 {
     if (instance()) {
         instance()->attachPin(capture, geometry);
@@ -122,7 +122,7 @@ void FlameshotDaemon::createPin(QPixmap capture, QRect geometry)
     call(m);
 }
 
-void FlameshotDaemon::copyToClipboard(QPixmap capture)
+void FlameshotDaemon::copyToClipboard(const QPixmap& capture)
 {
     if (instance()) {
         instance()->attachScreenshotToClipboard(capture);
@@ -140,7 +140,8 @@ void FlameshotDaemon::copyToClipboard(QPixmap capture)
     call(m);
 }
 
-void FlameshotDaemon::copyToClipboard(QString text, QString notification)
+void FlameshotDaemon::copyToClipboard(const QString& text,
+                                      const QString& notification)
 {
     if (instance()) {
         instance()->attachTextToClipboard(text, notification);
@@ -187,12 +188,14 @@ void FlameshotDaemon::getLatestAvailableVersion()
 {
     // This features is required for MacOS and Windows user and for Linux users
     // who installed Flameshot not from the repository.
-    m_networkCheckUpdates = new QNetworkAccessManager(this);
     QNetworkRequest requestCheckUpdates(QUrl(FLAMESHOT_APP_VERSION_URL));
-    connect(m_networkCheckUpdates,
-            &QNetworkAccessManager::finished,
-            this,
-            &FlameshotDaemon::handleReplyCheckUpdates);
+    if (nullptr == m_networkCheckUpdates) {
+        m_networkCheckUpdates = new QNetworkAccessManager(this);
+        connect(m_networkCheckUpdates,
+                &QNetworkAccessManager::finished,
+                this,
+                &FlameshotDaemon::handleReplyCheckUpdates);
+    }
     m_networkCheckUpdates->get(requestCheckUpdates);
 
     // check for updates each 24 hours
@@ -253,7 +256,7 @@ void FlameshotDaemon::quitIfIdle()
 
 // SERVICE METHODS
 
-void FlameshotDaemon::attachPin(QPixmap pixmap, QRect geometry)
+void FlameshotDaemon::attachPin(const QPixmap& pixmap, QRect geometry)
 {
     auto* pinWidget = new PinWidget(pixmap, geometry);
     m_widgets.append(pinWidget);
@@ -266,7 +269,7 @@ void FlameshotDaemon::attachPin(QPixmap pixmap, QRect geometry)
     pinWidget->activateWindow();
 }
 
-void FlameshotDaemon::attachScreenshotToClipboard(QPixmap pixmap)
+void FlameshotDaemon::attachScreenshotToClipboard(const QPixmap& pixmap)
 {
     m_hostingClipboard = true;
     QClipboard* clipboard = QApplication::clipboard();
@@ -301,7 +304,8 @@ void FlameshotDaemon::attachScreenshotToClipboard(const QByteArray& screenshot)
     attachScreenshotToClipboard(p);
 }
 
-void FlameshotDaemon::attachTextToClipboard(QString text, QString notification)
+void FlameshotDaemon::attachTextToClipboard(const QString& text,
+                                            const QString& notification)
 {
     // Must send notification before clipboard modification on linux
     if (!notification.isEmpty()) {
@@ -391,7 +395,7 @@ void FlameshotDaemon::handleReplyCheckUpdates(QNetworkReply* reply)
 }
 #endif
 
-QDBusMessage FlameshotDaemon::createMethodCall(QString method)
+QDBusMessage FlameshotDaemon::createMethodCall(const QString& method)
 {
     QDBusMessage m =
       QDBusMessage::createMethodCall(QStringLiteral("org.flameshot.Flameshot"),
diff --git a/src/core/flameshotdaemon.h b/src/core/flameshotdaemon.h
index c729ce8a..e49c815e 100644
--- a/src/core/flameshotdaemon.h
+++ b/src/core/flameshotdaemon.h
@@ -23,9 +23,10 @@ class FlameshotDaemon : public QObject
 public:
     static void start();
     static FlameshotDaemon* instance();
-    static void createPin(QPixmap capture, QRect geometry);
-    static void copyToClipboard(QPixmap capture);
-    static void copyToClipboard(QString text, QString notification = "");
+    static void createPin(const QPixmap& capture, QRect geometry);
+    static void copyToClipboard(const QPixmap& capture);
+    static void copyToClipboard(const QString& text,
+                                const QString& notification = "");
     static bool isThisInstanceHostingWidgets();
 
     void sendTrayNotification(
@@ -50,17 +51,19 @@ signals:
 private:
     FlameshotDaemon();
     void quitIfIdle();
-    void attachPin(QPixmap pixmap, QRect geometry);
-    void attachScreenshotToClipboard(QPixmap pixmap);
+    void attachPin(const QPixmap& pixmap, QRect geometry);
+    void attachScreenshotToClipboard(const QPixmap& pixmap);
 
     void attachPin(const QByteArray& data);
     void attachScreenshotToClipboard(const QByteArray& screenshot);
-    void attachTextToClipboard(QString text, QString notification);
+    void attachTextToClipboard(const QString& text,
+                               const QString& notification);
 
     void initTrayIcon();
     void enableTrayIcon(bool enable);
 
-    static QDBusMessage createMethodCall(QString method);
+private:
+    static QDBusMessage createMethodCall(const QString& method);
     static void checkDBusConnection(const QDBusConnection& connection);
     static void call(const QDBusMessage& m);
 
diff --git a/src/core/flameshotdbusadapter.cpp b/src/core/flameshotdbusadapter.cpp
index 11632e9f..fc48b156 100644
--- a/src/core/flameshotdbusadapter.cpp
+++ b/src/core/flameshotdbusadapter.cpp
@@ -15,8 +15,8 @@ void FlameshotDBusAdapter::attachScreenshotToClipboard(const QByteArray& data)
     FlameshotDaemon::instance()->attachScreenshotToClipboard(data);
 }
 
-void FlameshotDBusAdapter::attachTextToClipboard(QString text,
-                                                 QString notification)
+void FlameshotDBusAdapter::attachTextToClipboard(const QString& text,
+                                                 const QString& notification)
 {
     FlameshotDaemon::instance()->attachTextToClipboard(text, notification);
 }
diff --git a/src/core/flameshotdbusadapter.h b/src/core/flameshotdbusadapter.h
index d9e96632..eb46d1d6 100644
--- a/src/core/flameshotdbusadapter.h
+++ b/src/core/flameshotdbusadapter.h
@@ -16,6 +16,7 @@ public:
 
 public slots:
     Q_NOREPLY void attachScreenshotToClipboard(const QByteArray& data);
-    Q_NOREPLY void attachTextToClipboard(QString text, QString notification);
+    Q_NOREPLY void attachTextToClipboard(const QString& text,
+                                         const QString& notification);
     Q_NOREPLY void attachPin(const QByteArray& data);
 };
diff --git a/src/tools/capturetool.h b/src/tools/capturetool.h
index e9fc669f..a095d618 100644
--- a/src/tools/capturetool.h
+++ b/src/tools/capturetool.h
@@ -191,7 +191,7 @@ public slots:
     virtual void drawMoveWithAdjustment(const QPoint& p) { drawMove(p); }
     // Called when the tool is activated.
     virtual void drawStart(const CaptureContext& context) = 0;
-    // Called right after pressign the button which activates the tool.
+    // Called right after pressing the button which activates the tool.
     virtual void pressed(CaptureContext& context) = 0;
     // Called when the color is changed in the editor.
     virtual void onColorChanged(const QColor& c) = 0;
diff --git a/src/tools/launcher/terminallauncher.cpp b/src/tools/launcher/terminallauncher.cpp
index 4c0aa204..3b9b810a 100644
--- a/src/tools/launcher/terminallauncher.cpp
+++ b/src/tools/launcher/terminallauncher.cpp
@@ -44,6 +44,5 @@ TerminalApp TerminalLauncher::getPreferedTerminal()
 bool TerminalLauncher::launchDetached(const QString& command)
 {
     TerminalApp app = getPreferedTerminal();
-    QString s = app.name + " " + app.arg + " " + command;
     return QProcess::startDetached(app.name, { app.arg, command });
 }
diff --git a/src/tools/text/texttool.cpp b/src/tools/text/texttool.cpp
index 798688a3..30fbfd4e 100644
--- a/src/tools/text/texttool.cpp
+++ b/src/tools/text/texttool.cpp
@@ -203,10 +203,10 @@ void TextTool::process(QPainter& painter, const QPixmap& pixmap)
     QFont orig_font = painter.font();
     QPen orig_pen = painter.pen();
     QFontMetrics fm(m_font);
-    QSize size(fm.boundingRect(QRect(), 0, m_text).size());
-    size.setWidth(size.width() + val * 2);
-    size.setHeight(size.height() + val * 2);
-    m_textArea.setSize(size);
+    QSize fontsize(fm.boundingRect(QRect(), 0, m_text).size());
+    fontsize.setWidth(fontsize.width() + val * 2);
+    fontsize.setHeight(fontsize.height() + val * 2);
+    m_textArea.setSize(fontsize);
     // draw text
     painter.setFont(m_font);
     painter.setPen(m_color);
diff --git a/src/utils/abstractlogger.cpp b/src/utils/abstractlogger.cpp
index 3de73e28..986cd602 100644
--- a/src/utils/abstractlogger.cpp
+++ b/src/utils/abstractlogger.cpp
@@ -45,7 +45,7 @@ AbstractLogger AbstractLogger::error(int targets)
     return { Error, targets };
 }
 
-AbstractLogger& AbstractLogger::sendMessage(QString msg, Channel channel)
+AbstractLogger& AbstractLogger::sendMessage(const QString& msg, Channel channel)
 {
     if (m_targets & Notification) {
         SystemNotification().sendMessage(
@@ -77,7 +77,7 @@ AbstractLogger& AbstractLogger::sendMessage(QString msg, Channel channel)
  * @param msg
  * @return
  */
-AbstractLogger& AbstractLogger::operator<<(QString msg)
+AbstractLogger& AbstractLogger::operator<<(const QString& msg)
 {
     sendMessage(msg, m_defaultChannel);
     return *this;
@@ -92,7 +92,7 @@ AbstractLogger& AbstractLogger::addOutputString(QString& str)
 /**
  * @brief Attach a path to a notification so it can be dragged and dropped.
  */
-AbstractLogger& AbstractLogger::attachNotificationPath(QString path)
+AbstractLogger& AbstractLogger::attachNotificationPath(const QString& path)
 {
     if (m_targets & Notification) {
         m_notificationPath = path;
diff --git a/src/utils/abstractlogger.h b/src/utils/abstractlogger.h
index 05ce8af5..6fc8ff7f 100644
--- a/src/utils/abstractlogger.h
+++ b/src/utils/abstractlogger.h
@@ -37,10 +37,10 @@ public:
     static AbstractLogger warning(int targets = Default);
     static AbstractLogger error(int targets = Default);
 
-    AbstractLogger& sendMessage(QString msg, Channel channel);
-    AbstractLogger& operator<<(QString msg);
+    AbstractLogger& sendMessage(const QString& msg, Channel channel);
+    AbstractLogger& operator<<(const QString& msg);
     AbstractLogger& addOutputString(QString& str);
-    AbstractLogger& attachNotificationPath(QString path);
+    AbstractLogger& attachNotificationPath(const QString& path);
     AbstractLogger& enableMessageHeader(bool enable);
 
 private:
diff --git a/src/utils/confighandler.cpp b/src/utils/confighandler.cpp
index b77b964e..effe4cb1 100644
--- a/src/utils/confighandler.cpp
+++ b/src/utils/confighandler.cpp
@@ -321,9 +321,9 @@ void ConfigHandler::setStartupLaunch(const bool start)
 
 void ConfigHandler::setAllTheButtons()
 {
-    QList<CaptureTool::Type> buttons =
+    QList<CaptureTool::Type> buttonlist =
       CaptureToolButton::getIterableButtonTypes();
-    setValue(QStringLiteral("buttons"), QVariant::fromValue(buttons));
+    setValue(QStringLiteral("buttons"), QVariant::fromValue(buttonlist));
 }
 
 void ConfigHandler::setToolSize(CaptureTool::Type toolType, int size)
@@ -388,16 +388,16 @@ bool ConfigHandler::setShortcut(const QString& actionName,
         return false;
     }
 
-    bool error = false;
+    bool errorFlag = false;
 
     m_settings.beginGroup(CONFIG_GROUP_SHORTCUTS);
     if (shortcut.isEmpty()) {
         setValue(actionName, "");
     } else if (reservedShortcuts.contains(QKeySequence(shortcut))) {
         // do not allow to set reserved shortcuts
-        error = true;
+        errorFlag = true;
     } else {
-        error = false;
+        errorFlag = false;
         // Make no difference for Return and Enter keys
         QString newShortcut = KeySequence().value(shortcut).toString();
         for (auto& otherAction : m_settings.allKeys()) {
@@ -407,7 +407,7 @@ bool ConfigHandler::setShortcut(const QString& actionName,
             QString existingShortcut =
               KeySequence().value(m_settings.value(otherAction)).toString();
             if (newShortcut == existingShortcut) {
-                error = true;
+                errorFlag = true;
                 goto done;
             }
         }
@@ -415,7 +415,7 @@ bool ConfigHandler::setShortcut(const QString& actionName,
     }
 done:
     m_settings.endGroup();
-    return !error;
+    return !errorFlag;
 }
 
 QString ConfigHandler::shortcut(const QString& actionName)
@@ -787,7 +787,7 @@ bool ConfigHandler::isShortcut(const QString& key) const
            key.startsWith(QStringLiteral(CONFIG_GROUP_SHORTCUTS "/"));
 }
 
-QString ConfigHandler::baseName(QString key) const
+QString ConfigHandler::baseName(const QString& key) const
 {
     return QFileInfo(key).baseName();
 }
diff --git a/src/utils/confighandler.h b/src/utils/confighandler.h
index e8f47754..62f653e7 100644
--- a/src/utils/confighandler.h
+++ b/src/utils/confighandler.h
@@ -178,6 +178,6 @@ private:
     QSharedPointer<ValueHandler> valueHandler(const QString& key) const;
     void assertKeyRecognized(const QString& key) const;
     bool isShortcut(const QString& key) const;
-    QString baseName(QString key) const;
+    QString baseName(const QString& key) const;
     void cleanUnusedKeys(const QString& group, const QSet<QString>& keys) const;
 };
diff --git a/src/utils/filenamehandler.cpp b/src/utils/filenamehandler.cpp
index ffee2569..4e3aa392 100644
--- a/src/utils/filenamehandler.cpp
+++ b/src/utils/filenamehandler.cpp
@@ -102,7 +102,7 @@ QString FileNameHandler::properScreenshotPath(QString path,
     }
 }
 
-QString FileNameHandler::autoNumerateDuplicate(QString path)
+QString FileNameHandler::autoNumerateDuplicate(const QString& path)
 {
     // add numeration in case of repeated filename in the directory
     // find unused name adding _n where n is a number
diff --git a/src/utils/filenamehandler.h b/src/utils/filenamehandler.h
index 921029ba..88c720ef 100644
--- a/src/utils/filenamehandler.h
+++ b/src/utils/filenamehandler.h
@@ -20,5 +20,5 @@ public:
     static const int MAX_CHARACTERS = 70;
 
 private:
-    QString autoNumerateDuplicate(QString path);
+    QString autoNumerateDuplicate(const QString& path);
 };
diff --git a/src/utils/history.cpp b/src/utils/history.cpp
index e1f8d37e..f3ee09d0 100644
--- a/src/utils/history.cpp
+++ b/src/utils/history.cpp
@@ -12,9 +12,9 @@ History::History()
 #ifdef Q_OS_WIN
     m_historyPath = QDir::homePath() + "/AppData/Roaming/flameshot/history/";
 #else
-    QString path = QProcessEnvironment::systemEnvironment().value(
+    QString cachepath = QProcessEnvironment::systemEnvironment().value(
       "XDG_CACHE_HOME", QDir::homePath() + "/.cache");
-    m_historyPath = path + "/flameshot/history/";
+    m_historyPath = cachepath + "/flameshot/history/";
 #endif
 
     // Check if directory for history exists and create if doesn't
diff --git a/src/utils/pathinfo.cpp b/src/utils/pathinfo.cpp
index 6b2ad5e4..ea3faf67 100644
--- a/src/utils/pathinfo.cpp
+++ b/src/utils/pathinfo.cpp
@@ -26,7 +26,6 @@ QStringList PathInfo::translationsPaths()
            << QStringLiteral(APP_PREFIX) + "/share/flameshot/translations"
            << trPath << QStringLiteral("/usr/share/flameshot/translations")
            << QStringLiteral("/usr/local/share/flameshot/translations");
-#elif defined(Q_OS_WIN)
-    return QStringList() << trPath;
 #endif
+    return QStringList() << trPath;
 }
diff --git a/src/utils/valuehandler.cpp b/src/utils/valuehandler.cpp
index 281e71ff..099255d6 100644
--- a/src/utils/valuehandler.cpp
+++ b/src/utils/valuehandler.cpp
@@ -513,7 +513,7 @@ QString SaveFileExtension::expected()
 bool Region::check(const QVariant& val)
 {
     QVariant region = process(val);
-    return process(val).isValid();
+    return region.isValid();
 }
 
 #include <QApplication> // TODO remove after FIXME (see below)
diff --git a/src/widgets/capture/buttonhandler.cpp b/src/widgets/capture/buttonhandler.cpp
index afd10754..4a003714 100644
--- a/src/widgets/capture/buttonhandler.cpp
+++ b/src/widgets/capture/buttonhandler.cpp
@@ -353,7 +353,7 @@ void ButtonHandler::adjustHorizontalCenter(QPoint& center)
 }
 
 // setButtons redefines the buttons of the button handler
-void ButtonHandler::setButtons(const QVector<CaptureToolButton*> v)
+void ButtonHandler::setButtons(const QVector<CaptureToolButton*>& v)
 {
     if (v.isEmpty()) {
         return;
diff --git a/src/widgets/capture/buttonhandler.h b/src/widgets/capture/buttonhandler.h
index bd694653..ca59971e 100644
--- a/src/widgets/capture/buttonhandler.h
+++ b/src/widgets/capture/buttonhandler.h
@@ -26,7 +26,7 @@ public:
     bool buttonsAreInside() const;
     size_t size() const;
 
-    void setButtons(const QVector<CaptureToolButton*>);
+    void setButtons(const QVector<CaptureToolButton*>&);
     bool contains(const QPoint& p) const;
     void updateScreenRegions(const QVector<QRect>& rects);
     void updateScreenRegions(const QRect& rect);
diff --git a/src/widgets/capture/capturetoolobjects.cpp b/src/widgets/capture/capturetoolobjects.cpp
index b0159f22..969492ec 100644
--- a/src/widgets/capture/capturetoolobjects.cpp
+++ b/src/widgets/capture/capturetoolobjects.cpp
@@ -61,7 +61,7 @@ void CaptureToolObjects::removeAt(int index)
     }
 }
 
-int CaptureToolObjects::find(const QPoint& pos, const QSize& captureSize)
+int CaptureToolObjects::find(const QPoint& pos, QSize captureSize)
 {
     if (m_captureToolObjects.empty()) {
         return -1;
diff --git a/src/widgets/capture/capturetoolobjects.h b/src/widgets/capture/capturetoolobjects.h
index 296479af..5c1f0447 100644
--- a/src/widgets/capture/capturetoolobjects.h
+++ b/src/widgets/capture/capturetoolobjects.h
@@ -18,7 +18,7 @@ public:
     void removeAt(int index);
     void clear();
     int size();
-    int find(const QPoint& pos, const QSize& captureSize);
+    int find(const QPoint& pos, QSize captureSize);
     QPointer<CaptureTool> at(int index);
     CaptureToolObjects& operator=(const CaptureToolObjects& other);
 
diff --git a/src/widgets/capture/capturewidget.cpp b/src/widgets/capture/capturewidget.cpp
index c12f03b0..3d535663 100644
--- a/src/widgets/capture/capturewidget.cpp
+++ b/src/widgets/capture/capturewidget.cpp
@@ -56,29 +56,27 @@ CaptureWidget::CaptureWidget(const CaptureRequest& req,
                              bool fullScreen,
                              QWidget* parent)
   : QWidget(parent)
+  , m_toolSizeByKeyboard(0)
   , m_mouseIsClicked(false)
   , m_captureDone(false)
   , m_previewEnabled(true)
   , m_adjustmentButtonPressed(false)
   , m_configError(false)
   , m_configErrorResolved(false)
+  , m_updateNotificationWidget(nullptr)
+  , m_lastMouseWheel(0)
   , m_activeButton(nullptr)
   , m_activeTool(nullptr)
-  , m_toolWidget(nullptr)
-  , m_colorPicker(nullptr)
-  , m_lastMouseWheel(0)
-#if !defined(DISABLE_UPDATE_CHECKER)
-  , m_updateNotificationWidget(nullptr)
-#endif
   , m_activeToolIsMoved(false)
+  , m_toolWidget(nullptr)
   , m_panel(nullptr)
   , m_sidePanel(nullptr)
+  , m_colorPicker(nullptr)
   , m_selection(nullptr)
   , m_magnifier(nullptr)
+  , m_xywhDisplay(false)
   , m_existingObjectIsChanged(false)
   , m_startMove(false)
-  , m_toolSizeByKeyboard(0)
-  , m_xywhDisplay(false)
 
 {
     m_undoStack.setUndoLimit(ConfigHandler().undoLimit());
@@ -95,7 +93,7 @@ CaptureWidget::CaptureWidget(const CaptureRequest& req,
             this,
             &CaptureWidget::childLeave);
 
-    connect(&m_xywhTimer, SIGNAL(timeout()), this, SLOT(xywhTick()));
+    connect(&m_xywhTimer, &QTimer::timeout, this, &CaptureWidget::xywhTick);
     setAttribute(Qt::WA_DeleteOnClose);
     setAttribute(Qt::WA_QuitOnClose, false);
     m_opacity = m_config.contrastOpacity();
@@ -328,8 +326,8 @@ void CaptureWidget::initButtons()
                   ConfigHandler().shortcut(QVariant::fromValue(t).toString());
                 if (!shortcut.isNull()) {
                     auto shortcuts = newShortcut(shortcut, this, nullptr);
-                    for (auto* shortcut : shortcuts) {
-                        connect(shortcut, &QShortcut::activated, this, [=]() {
+                    for (auto* sc : shortcuts) {
+                        connect(sc, &QShortcut::activated, this, [=]() {
                             setState(b);
                         });
                     }
@@ -420,28 +418,26 @@ void CaptureWidget::showxywh(bool show)
 void CaptureWidget::initHelpMessage()
 {
     QList<QPair<QString, QString>> keyMap;
-    if (keyMap.isEmpty()) {
-        keyMap << QPair(tr("Mouse"), tr("Select screenshot area"));
-        using CT = CaptureTool;
-        for (auto toolType :
-             { CT::TYPE_ACCEPT, CT::TYPE_SAVE, CT::TYPE_COPY }) {
-            if (!m_tools.contains(toolType)) {
-                continue;
-            }
-            auto* tool = m_tools[toolType];
-            QString shortcut = ConfigHandler().shortcut(
-              QVariant::fromValue(toolType).toString());
-            shortcut.replace("Return", "Enter");
-            if (!shortcut.isEmpty()) {
-                keyMap << QPair(shortcut, tool->description());
-            }
+    keyMap << QPair(tr("Mouse"), tr("Select screenshot area"));
+    using CT = CaptureTool;
+    for (auto toolType : { CT::TYPE_ACCEPT, CT::TYPE_SAVE, CT::TYPE_COPY }) {
+        if (!m_tools.contains(toolType)) {
+            continue;
+        }
+        auto* tool = m_tools[toolType];
+        QString shortcut =
+          ConfigHandler().shortcut(QVariant::fromValue(toolType).toString());
+        shortcut.replace("Return", "Enter");
+        if (!shortcut.isEmpty()) {
+            keyMap << QPair(shortcut, tool->description());
         }
-        keyMap << QPair(tr("Mouse Wheel"), tr("Change tool size"));
-        keyMap << QPair(tr("Right Click"), tr("Show color picker"));
-        keyMap << QPair(ConfigHandler().shortcut("TYPE_TOGGLE_PANEL"),
-                        tr("Open side panel"));
-        keyMap << QPair(tr("Esc"), tr("Exit"));
     }
+    keyMap << QPair(tr("Mouse Wheel"), tr("Change tool size"));
+    keyMap << QPair(tr("Right Click"), tr("Show color picker"));
+    keyMap << QPair(ConfigHandler().shortcut("TYPE_TOGGLE_PANEL"),
+                    tr("Open side panel"));
+    keyMap << QPair(tr("Esc"), tr("Exit"));
+
     m_helpMessage = OverlayMessage::compileFromKeyMap(keyMap);
 }
 
@@ -1499,15 +1495,13 @@ void CaptureWidget::removeToolObject(int index)
     --index;
     if (index >= 0 && index < m_captureToolObjects.size()) {
         // in case this tool is circle counter
-        int removedCircleCount = -1;
-
         const CaptureTool::Type currentToolType =
           m_captureToolObjects.at(index)->type();
         m_captureToolObjectsBackup = m_captureToolObjects;
         update(
           paddedUpdateRect(m_captureToolObjects.at(index)->boundingRect()));
         if (currentToolType == CaptureTool::TYPE_CIRCLECOUNT) {
-            removedCircleCount = m_captureToolObjects.at(index)->count();
+            int removedCircleCount = m_captureToolObjects.at(index)->count();
             --m_context.circleCount;
             // Decrement circle counter numbers starting from deleted circle
             for (int cnt = 0; cnt < m_captureToolObjects.size(); cnt++) {
diff --git a/src/widgets/capture/selectionwidget.cpp b/src/widgets/capture/selectionwidget.cpp
index 68c208e2..5e5fe355 100644
--- a/src/widgets/capture/selectionwidget.cpp
+++ b/src/widgets/capture/selectionwidget.cpp
@@ -384,8 +384,8 @@ void SelectionWidget::paintEvent(QPaintEvent*)
     p.drawRect(rect() + QMargins(0, 0, -1, -1));
     p.setRenderHint(QPainter::Antialiasing);
     p.setBrush(m_color);
-    for (auto rect : handlerAreas()) {
-        p.drawEllipse(rect);
+    for (auto rectangle : handlerAreas()) {
+        p.drawEllipse(rectangle);
     }
 }
 
@@ -549,14 +549,14 @@ void SelectionWidget::updateCursor()
 void SelectionWidget::setGeometryByKeyboard(const QRect& r)
 {
     static QTimer timer;
-    QRect rect = r.intersected(parentWidget()->rect());
-    if (rect.width() <= 0) {
-        rect.setWidth(1);
+    QRect rectangle = r.intersected(parentWidget()->rect());
+    if (rectangle.width() <= 0) {
+        rectangle.setWidth(1);
     }
-    if (rect.height() <= 0) {
-        rect.setHeight(1);
+    if (rectangle.height() <= 0) {
+        rectangle.setHeight(1);
     }
-    setGeometry(rect);
+    setGeometry(rectangle);
     connect(&timer,
             &QTimer::timeout,
             this,
diff --git a/src/widgets/orientablepushbutton.cpp b/src/widgets/orientablepushbutton.cpp
index c387e6df..091397d4 100644
--- a/src/widgets/orientablepushbutton.cpp
+++ b/src/widgets/orientablepushbutton.cpp
@@ -62,7 +62,7 @@ OrientablePushButton::Orientation OrientablePushButton::orientation() const
 }
 
 void OrientablePushButton::setOrientation(
-  const OrientablePushButton::Orientation& orientation)
+  OrientablePushButton::Orientation orientation)
 {
     m_orientation = orientation;
 }
diff --git a/src/widgets/orientablepushbutton.h b/src/widgets/orientablepushbutton.h
index 9f4cab11..0082ff4c 100644
--- a/src/widgets/orientablepushbutton.h
+++ b/src/widgets/orientablepushbutton.h
@@ -28,7 +28,7 @@ public:
     QSize sizeHint() const;
 
     OrientablePushButton::Orientation orientation() const;
-    void setOrientation(const OrientablePushButton::Orientation& orientation);
+    void setOrientation(OrientablePushButton::Orientation orientation);
 
 protected:
     void paintEvent(QPaintEvent* event);
diff --git a/src/widgets/panel/utilitypanel.cpp b/src/widgets/panel/utilitypanel.cpp
index 18401b4f..5fc1889e 100644
--- a/src/widgets/panel/utilitypanel.cpp
+++ b/src/widgets/panel/utilitypanel.cpp
@@ -137,9 +137,9 @@ void UtilityPanel::initInternalPanel()
 
     m_captureTools = new QListWidget(this);
     connect(m_captureTools,
-            SIGNAL(currentRowChanged(int)),
+            &QListWidget::currentRowChanged,
             this,
-            SLOT(onCurrentRowChanged(int)));
+            &UtilityPanel::onCurrentRowChanged);
 
     auto* layersButtons = new QHBoxLayout();
     m_layersLayout->addLayout(layersButtons);
@@ -171,9 +171,9 @@ void UtilityPanel::initInternalPanel()
     layersButtons->addStretch();
 
     connect(m_buttonDelete,
-            SIGNAL(clicked(bool)),
+            &QPushButton::clicked,
             this,
-            SLOT(slotButtonDelete(bool)));
+            &UtilityPanel::slotButtonDelete);
 
     connect(m_buttonMoveUp,
             &QPushButton::clicked,
diff --git a/src/widgets/trayicon.cpp b/src/widgets/trayicon.cpp
index cb4de571..df58271c 100644
--- a/src/widgets/trayicon.cpp
+++ b/src/widgets/trayicon.cpp
@@ -139,7 +139,7 @@ void TrayIcon::initMenu()
     connect(FlameshotDaemon::instance(),
             &FlameshotDaemon::newVersionAvailable,
             this,
-            [this](QVersionNumber version) {
+            [this](const QVersionNumber& version) {
                 QString newVersion =
                   tr("New version %1 is available").arg(version.toString());
                 m_appUpdates->setText(newVersion);