diff --git a/src/base/net/geoipdatabase.cpp b/src/base/net/geoipdatabase.cpp
index 34260c625..0379e83fa 100644
--- a/src/base/net/geoipdatabase.cpp
+++ b/src/base/net/geoipdatabase.cpp
@@ -516,3 +516,22 @@ QVariant GeoIPDatabase::readArrayValue(quint32 &offset, const quint32 count) con
 
     return array;
 }
+
+template <typename T>
+QVariant GeoIPDatabase::readPlainValue(quint32 &offset, const quint8 len) const
+{
+    T value = 0;
+    const uchar *const data = m_data + offset;
+    const quint32 availSize = m_size - offset;
+
+    if ((len > 0) && (len <= sizeof(T) && (availSize >= len)))
+    {
+        // copy input data to last 'len' bytes of 'value'
+        uchar *dst = reinterpret_cast<uchar *>(&value) + (sizeof(T) - len);
+        memcpy(dst, data, len);
+        fromBigEndian(reinterpret_cast<uchar *>(&value), sizeof(T));
+        offset += len;
+    }
+
+    return QVariant::fromValue(value);
+}
diff --git a/src/base/net/geoipdatabase.h b/src/base/net/geoipdatabase.h
index f0b2b6400..3d9495c10 100644
--- a/src/base/net/geoipdatabase.h
+++ b/src/base/net/geoipdatabase.h
@@ -70,24 +70,7 @@ private:
     QVariant readMapValue(quint32 &offset, quint32 count) const;
     QVariant readArrayValue(quint32 &offset, quint32 count) const;
 
-    template<typename T>
-    QVariant readPlainValue(quint32 &offset, quint8 len) const
-    {
-        T value = 0;
-        const uchar *const data = m_data + offset;
-        const quint32 availSize = m_size - offset;
-
-        if ((len > 0) && (len <= sizeof(T) && (availSize >= len)))
-        {
-            // copy input data to last 'len' bytes of 'value'
-            uchar *dst = reinterpret_cast<uchar *>(&value) + (sizeof(T) - len);
-            memcpy(dst, data, len);
-            fromBigEndian(reinterpret_cast<uchar *>(&value), sizeof(T));
-            offset += len;
-        }
-
-        return QVariant::fromValue(value);
-    }
+    template <typename T> QVariant readPlainValue(quint32 &offset, quint8 len) const;
 
     // Metadata
     quint16 m_ipVersion;
diff --git a/src/gui/advancedsettings.cpp b/src/gui/advancedsettings.cpp
index 5907762aa..306444213 100644
--- a/src/gui/advancedsettings.cpp
+++ b/src/gui/advancedsettings.cpp
@@ -156,7 +156,7 @@ AdvancedSettings::AdvancedSettings(QWidget *parent)
 {
     // column
     setColumnCount(COL_COUNT);
-    QStringList header = {tr("Setting"), tr("Value", "Value set for this setting")};
+    const QStringList header = {tr("Setting"), tr("Value", "Value set for this setting")};
     setHorizontalHeaderLabels(header);
     // row
     setRowCount(ROW_COUNT);
@@ -171,7 +171,7 @@ AdvancedSettings::AdvancedSettings(QWidget *parent)
     horizontalHeader()->setStretchLastSection(true);
 }
 
-void AdvancedSettings::saveAdvancedSettings()
+void AdvancedSettings::saveAdvancedSettings() const
 {
     Preferences *const pref = Preferences::instance();
     BitTorrent::Session *const session = BitTorrent::Session::instance();
@@ -314,7 +314,7 @@ void AdvancedSettings::saveAdvancedSettings()
 }
 
 #ifndef QBT_USES_LIBTORRENT2
-void AdvancedSettings::updateCacheSpinSuffix(int value)
+void AdvancedSettings::updateCacheSpinSuffix(const int value)
 {
     if (value == 0)
         m_spinBoxCache.setSuffix(tr(" (disabled)"));
diff --git a/src/gui/advancedsettings.h b/src/gui/advancedsettings.h
index 1dc52ebc6..8d42c741c 100644
--- a/src/gui/advancedsettings.h
+++ b/src/gui/advancedsettings.h
@@ -34,15 +34,16 @@
 #include <QSpinBox>
 #include <QTableWidget>
 
-class AdvancedSettings : public QTableWidget
+class AdvancedSettings final : public QTableWidget
 {
     Q_OBJECT
+    Q_DISABLE_COPY_MOVE(AdvancedSettings)
 
 public:
     AdvancedSettings(QWidget *parent);
 
 public slots:
-    void saveAdvancedSettings();
+    void saveAdvancedSettings() const;
 
 signals:
     void settingsChanged();