diff --git a/src/ui/db/databasemanager.h b/src/ui/db/databasemanager.h
index aa3cbe91..39ce44d5 100644
--- a/src/ui/db/databasemanager.h
+++ b/src/ui/db/databasemanager.h
@@ -1,8 +1,8 @@
 #ifndef DATABASEMANAGER_H
 #define DATABASEMANAGER_H
 
-#include <QObject>
 #include <QHash>
+#include <QObject>
 #include <QStringList>
 #include <QVector>
 
@@ -52,7 +52,7 @@ public slots:
     void clear();
 
 private:
-    typedef QList<SqliteStmt *> QStmtList;
+    using QStmtList = QList<SqliteStmt *>;
 
     void initializeQuota();
 
diff --git a/src/ui/fortmanager.cpp b/src/ui/fortmanager.cpp
index 23ed5976..974836ab 100644
--- a/src/ui/fortmanager.cpp
+++ b/src/ui/fortmanager.cpp
@@ -166,7 +166,7 @@ void FortManager::setupTrayIcon()
     m_trayIcon->setToolTip(qApp->applicationDisplayName());
     m_trayIcon->setIcon(QIcon(":/images/shield.png"));
 
-    connect(m_trayIcon, &QSystemTrayIcon::activated,
+    connect(m_trayIcon, &QSystemTrayIcon::activated, this,
             [this](QSystemTrayIcon::ActivationReason reason) {
         if (reason == QSystemTrayIcon::Trigger) {
             showWindow();
@@ -186,13 +186,14 @@ bool FortManager::setupEngine()
 
     m_engine->load(QUrl("qrc:/qml/main.qml"));
 
-    if (m_engine->rootObjects().isEmpty()) {
+    const QList<QObject *> rootObjects = m_engine->rootObjects();
+
+    if (rootObjects.isEmpty()) {
         showErrorBox("Cannot setup QML Engine");
         return false;
     }
 
-    m_appWindow = qobject_cast<QWindow *>(
-                m_engine->rootObjects().first());
+    m_appWindow = qobject_cast<QWindow *>(rootObjects.first());
     Q_ASSERT(m_appWindow);
 
     m_appWindowState->install(m_appWindow);
@@ -200,6 +201,16 @@ bool FortManager::setupEngine()
     return true;
 }
 
+void FortManager::closeEngine()
+{
+    m_appWindow = nullptr;
+
+    if (m_engine) {
+        m_engine->deleteLater();
+        m_engine = nullptr;
+    }
+}
+
 void FortManager::showTrayIcon()
 {
     m_trayIcon->show();
@@ -291,12 +302,7 @@ void FortManager::exit(int retcode)
     closeGraphWindow();
     closeWindow();
 
-    m_appWindow = nullptr;
-
-    if (m_engine) {
-        m_engine->deleteLater();
-        m_engine = nullptr;
-    }
+    closeEngine();
 
     qApp->exit(retcode);
 }
diff --git a/src/ui/fortmanager.h b/src/ui/fortmanager.h
index 0d3b2f05..bd64a70f 100644
--- a/src/ui/fortmanager.h
+++ b/src/ui/fortmanager.h
@@ -92,7 +92,9 @@ private:
     void setupLogManager();
 
     void setupTrayIcon();
+
     bool setupEngine();
+    void closeEngine();
 
     bool loadSettings(FirewallConf *conf);
     bool saveSettings(FirewallConf *newConf, bool onlyFlags = false,
diff --git a/src/ui/fortsettings.h b/src/ui/fortsettings.h
index 4f947e8d..444988e4 100644
--- a/src/ui/fortsettings.h
+++ b/src/ui/fortsettings.h
@@ -1,8 +1,8 @@
 #ifndef FORTSETTINGS_H
 #define FORTSETTINGS_H
 
-#include <QObject>
 #include <QHash>
+#include <QObject>
 #include <QRect>
 #include <QSettings>
 
@@ -10,7 +10,7 @@
 
 QT_FORWARD_DECLARE_CLASS(FirewallConf)
 
-typedef QHash<QString, QByteArray> TasksMap;
+using TasksMap = QHash<QString, QByteArray>;
 
 class FortSettings : public QObject
 {
diff --git a/src/ui/log/logentry.cpp b/src/ui/log/logentry.cpp
index 294943ff..76088050 100644
--- a/src/ui/log/logentry.cpp
+++ b/src/ui/log/logentry.cpp
@@ -3,14 +3,6 @@
 #include "../util/fileutil.h"
 #include "../util/osutil.h"
 
-LogEntry::LogEntry()
-{
-}
-
-LogEntry::~LogEntry()
-{
-}
-
 QString LogEntry::getAppPath(const QString &kernelPath, quint32 pid)
 {
     return kernelPath.isEmpty()
diff --git a/src/ui/log/logentry.h b/src/ui/log/logentry.h
index b8e42d52..a43f0405 100644
--- a/src/ui/log/logentry.h
+++ b/src/ui/log/logentry.h
@@ -14,8 +14,8 @@ public:
         StatTraf    = 0x04000000
     };
 
-    explicit LogEntry();
-    virtual ~LogEntry();
+    explicit LogEntry() = default;
+    virtual ~LogEntry() = default;
 
     virtual LogEntry::LogType type() const = 0;
 
diff --git a/src/ui/task/taskuzonline.cpp b/src/ui/task/taskuzonline.cpp
index 916940a4..95d5e1cd 100644
--- a/src/ui/task/taskuzonline.cpp
+++ b/src/ui/task/taskuzonline.cpp
@@ -22,7 +22,7 @@ QStringList TaskUzonline::parseUzonlineBuffer(const QByteArray &buffer)
     if (startPos < 0 || endPos < 0)
         return QStringList();
 
-    const QRegularExpression re("([\\d.]+)[^\\d.]*-[^\\d.]*([\\d.]+)");
+    const QRegularExpression re(R"(([\d.]+)[^\d.]*-[^\d.]*([\d.]+))");
 
     QStringList list;
 
diff --git a/src/ui/util/conf/confutil.cpp b/src/ui/util/conf/confutil.cpp
index 22617464..cd0812b9 100644
--- a/src/ui/util/conf/confutil.cpp
+++ b/src/ui/util/conf/confutil.cpp
@@ -189,7 +189,7 @@ bool ConfUtil::parseAppGroups(const QList<AppGroup *> &appGroups,
         appPerms.reserve(appPermsMap.size());
 
         for (; it != end; ++it) {
-            const QString appPath = it.key();
+            const QString &appPath = it.key();
             appPathsLen += appPath.size() * sizeof(wchar_t);
 
             appPaths.append(appPath);
@@ -240,7 +240,7 @@ bool ConfUtil::parseApps(const QString &text, bool blocked,
 
 QString ConfUtil::parseAppPath(const QStringRef &line)
 {
-    const QRegularExpression re("\\s*\"?\\s*([^\"]+)\\s*\"?\\s*");
+    const QRegularExpression re(R"(\s*"?\s*([^"]+)\s*"?\s*)");
     const QRegularExpressionMatch match = re.match(line);
 
     if (!match.hasMatch())
@@ -330,7 +330,6 @@ quint16 ConfUtil::writeLimits(struct fort_conf_limit *limits,
         limit->out_bytes = appGroup->enabled() && appGroup->limitOutEnabled()
                 ? appGroup->speedLimitOut() * 1024 / 2 : 0;
 
-        const quint16 bit = quint16(1 << i);
         if (limit->in_bytes || limit->out_bytes) {
             limitBits |= (1 << i);
         }
diff --git a/src/ui/util/conf/confutil.h b/src/ui/util/conf/confutil.h
index 5592090b..d889d471 100644
--- a/src/ui/util/conf/confutil.h
+++ b/src/ui/util/conf/confutil.h
@@ -15,12 +15,12 @@ QT_FORWARD_DECLARE_CLASS(FirewallConf)
 
 QT_FORWARD_DECLARE_STRUCT(fort_conf_limit)
 
-typedef QVector<quint32> numbers_arr_t;
+using numbers_arr_t = QVector<quint32>;
 
-typedef QVarLengthArray<AddressRange, 2> addrranges_arr_t;
+using addrranges_arr_t = QVarLengthArray<AddressRange, 2>;
 
-typedef QMap<QString, quint32> appperms_map_t;
-typedef QMap<QString, qint8> appgroups_map_t;
+using appperms_map_t = QMap<QString, quint32>;
+using appgroups_map_t = QMap<QString, qint8>;
 
 class ConfUtil : public QObject
 {
diff --git a/src/ui/util/device.cpp b/src/ui/util/device.cpp
index a47c8b47..07e42626 100644
--- a/src/ui/util/device.cpp
+++ b/src/ui/util/device.cpp
@@ -30,7 +30,8 @@ bool Device::open(const QString &filePath)
             | SECURITY_SQOS_PRESENT | SECURITY_IDENTIFICATION;
 
     m_handle = CreateFileW((LPCWSTR) filePath.utf16(),
-                           access, share, NULL, creation, attr, NULL);
+                           access, share, nullptr,
+                           creation, attr, nullptr);
 
     return m_handle != INVALID_HANDLE_VALUE;
 }
@@ -47,7 +48,7 @@ bool Device::close()
 
 bool Device::cancelIo()
 {
-    return CancelIoEx(m_handle, NULL);
+    return CancelIoEx(m_handle, nullptr);
 }
 
 bool Device::ioctl(quint32 code, char *in, int inSize,
@@ -58,7 +59,7 @@ bool Device::ioctl(quint32 code, char *in, int inSize,
     const bool res = DeviceIoControl(
                 m_handle, code,
                 in, inSize, out, outSize,
-                &size, NULL);
+                &size, nullptr);
 
     if (retSize) {
         *retSize = size;
diff --git a/src/ui/util/net/ip4range.cpp b/src/ui/util/net/ip4range.cpp
index 04054c3a..f9a455a1 100644
--- a/src/ui/util/net/ip4range.cpp
+++ b/src/ui/util/net/ip4range.cpp
@@ -95,7 +95,7 @@ bool Ip4Range::fromText(const QString &text)
 bool Ip4Range::parseAddressMask(const QStringRef &line,
                                 quint32 &from, quint32 &to)
 {
-    const QRegularExpression re("([\\d.]+)\\s*([/-]?)\\s*(\\S*)");
+    const QRegularExpression re(R"(([\d.]+)\s*([/-]?)\s*(\S*))");
     const QRegularExpressionMatch match = re.match(line);
 
     if (!match.hasMatch()) {
diff --git a/src/ui/util/net/ip4range.h b/src/ui/util/net/ip4range.h
index 211283ff..2c6f6e00 100644
--- a/src/ui/util/net/ip4range.h
+++ b/src/ui/util/net/ip4range.h
@@ -1,16 +1,16 @@
 #ifndef IP4RANGE_H
 #define IP4RANGE_H
 
-#include <QObject>
 #include <QMap>
+#include <QObject>
 #include <QVector>
 
-typedef struct {
+using Ip4Pair = struct {
     quint32 from, to;
-} Ip4Pair;
+};
 
-typedef QMap<quint32, quint32> ip4range_map_t;
-typedef QVector<quint32> ip4range_arr_t;
+using ip4range_map_t = QMap<quint32, quint32>;
+using ip4range_arr_t = QVector<quint32>;
 
 class Ip4Range : public QObject
 {
@@ -30,7 +30,7 @@ public:
     const ip4range_arr_t &fromArray() const { return m_fromArray; }
     const ip4range_arr_t &toArray() const { return m_toArray; }
 
-    const int size() const { return m_toArray.size(); }
+    int size() const { return m_toArray.size(); }
     const Ip4Pair at(int i) const {
         return Ip4Pair{m_fromArray.at(i), m_toArray.at(i)};
     }
diff --git a/src/ui/util/osutil.cpp b/src/ui/util/osutil.cpp
index 81ea53b3..32e88e73 100644
--- a/src/ui/util/osutil.cpp
+++ b/src/ui/util/osutil.cpp
@@ -18,7 +18,7 @@ QString OsUtil::pidToPath(quint32 pid, bool isKernelPath)
 
 bool OsUtil::createGlobalMutex(const char *name)
 {
-    return !CreateMutexA(NULL, FALSE, name);
+    return !CreateMutexA(nullptr, FALSE, name);
 }
 
 quint32 OsUtil::lastErrorCode()
@@ -28,12 +28,13 @@ quint32 OsUtil::lastErrorCode()
 
 QString OsUtil::lastErrorMessage(quint32 errorCode)
 {
-    LPWSTR buf = NULL;
+    LPWSTR buf = nullptr;
 
     FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER
                    | FORMAT_MESSAGE_FROM_SYSTEM
                    | FORMAT_MESSAGE_IGNORE_INSERTS,
-                   NULL, errorCode, 0, (LPWSTR) &buf, 0, NULL);
+                   nullptr, errorCode, 0,
+                   (LPWSTR) &buf, 0, nullptr);
 
     if (!buf) {
         return QString("System Error %1").arg(errorCode);