diff --git a/3rdparty/singleapplication/singleapplication.cpp b/3rdparty/singleapplication/singleapplication.cpp
index 1dc4c7c8..b0a0b9fa 100644
--- a/3rdparty/singleapplication/singleapplication.cpp
+++ b/3rdparty/singleapplication/singleapplication.cpp
@@ -178,7 +178,7 @@ SingleApplication::~SingleApplication() {
  * Checks if the current application instance is primary.
  * @return Returns true if the instance is primary, false otherwise.
  */
-bool SingleApplication::isPrimary() {
+bool SingleApplication::isPrimary() const {
   Q_D(SingleApplication);
   return d->server_ != nullptr;
 }
@@ -187,7 +187,7 @@ bool SingleApplication::isPrimary() {
  * Checks if the current application instance is secondary.
  * @return Returns true if the instance is secondary, false otherwise.
  */
-bool SingleApplication::isSecondary() {
+bool SingleApplication::isSecondary() const {
   Q_D(SingleApplication);
   return d->server_ == nullptr;
 }
@@ -197,7 +197,7 @@ bool SingleApplication::isSecondary() {
  * It is reset when the first (primary) instance of your app starts and only incremented afterwards.
  * @return Returns a unique instance id.
  */
-quint32 SingleApplication::instanceId() {
+quint32 SingleApplication::instanceId() const {
   Q_D(SingleApplication);
   return d->instanceNumber_;
 }
@@ -207,7 +207,7 @@ quint32 SingleApplication::instanceId() {
  * Especially useful when SingleApplication is coupled with OS. specific APIs.
  * @return Returns the primary instance PID.
  */
-qint64 SingleApplication::primaryPid() {
+qint64 SingleApplication::primaryPid() const {
   Q_D(SingleApplication);
   return d->primaryPid();
 }
@@ -216,7 +216,7 @@ qint64 SingleApplication::primaryPid() {
  * Returns the username the primary instance is running as.
  * @return Returns the username the primary instance is running as.
  */
-QString SingleApplication::primaryUser() {
+QString SingleApplication::primaryUser() const {
   Q_D(SingleApplication);
   return d->primaryUser();
 }
@@ -225,7 +225,7 @@ QString SingleApplication::primaryUser() {
  * Returns the username the current instance is running as.
  * @return Returns the username the current instance is running as.
  */
-QString SingleApplication::currentUser() {
+QString SingleApplication::currentUser() const {
   Q_D(SingleApplication);
   return d->getUsername();
 }
diff --git a/3rdparty/singleapplication/singleapplication.h b/3rdparty/singleapplication/singleapplication.h
index 8a3ca290..c7c83155 100644
--- a/3rdparty/singleapplication/singleapplication.h
+++ b/3rdparty/singleapplication/singleapplication.h
@@ -97,37 +97,37 @@ class SingleApplication : public QApplication {  // clazy:exclude=ctor-missing-p
    * @brief Returns if the instance is the primary instance
    * @returns {bool}
    */
-  bool isPrimary();
+  bool isPrimary() const;
 
   /**
    * @brief Returns if the instance is a secondary instance
    * @returns {bool}
    */
-  bool isSecondary();
+  bool isSecondary() const;
 
   /**
    * @brief Returns a unique identifier for the current instance
    * @returns {qint32}
    */
-  quint32 instanceId();
+  quint32 instanceId() const;
 
   /**
    * @brief Returns the process ID (PID) of the primary instance
    * @returns {qint64}
    */
-  qint64 primaryPid();
+  qint64 primaryPid() const;
 
   /**
    * @brief Returns the username of the user running the primary instance
    * @returns {QString}
    */
-  QString primaryUser();
+  QString primaryUser() const;
 
   /**
    * @brief Returns the username of the current user
    * @returns {QString}
    */
-  QString currentUser();
+  QString currentUser() const;
 
   /**
    * @brief Sends a message to the primary instance. Returns true on success.
diff --git a/3rdparty/singleapplication/singleapplication_p.cpp b/3rdparty/singleapplication/singleapplication_p.cpp
index d08bc04b..2aeac871 100644
--- a/3rdparty/singleapplication/singleapplication_p.cpp
+++ b/3rdparty/singleapplication/singleapplication_p.cpp
@@ -284,7 +284,7 @@ bool SingleApplicationPrivate::connectToPrimary(const int timeout, const Connect
 
 }
 
-quint16 SingleApplicationPrivate::blockChecksum() {
+quint16 SingleApplicationPrivate::blockChecksum() const {
 
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
   quint16 checksum = qChecksum(QByteArray(static_cast<const char*>(memory_->constData()), offsetof(InstancesInfo, checksum)));
@@ -296,7 +296,7 @@ quint16 SingleApplicationPrivate::blockChecksum() {
 
 }
 
-qint64 SingleApplicationPrivate::primaryPid() {
+qint64 SingleApplicationPrivate::primaryPid() const {
 
   memory_->lock();
   InstancesInfo *inst = static_cast<InstancesInfo*>(memory_->data());
@@ -307,7 +307,7 @@ qint64 SingleApplicationPrivate::primaryPid() {
 
 }
 
-QString SingleApplicationPrivate::primaryUser() {
+QString SingleApplicationPrivate::primaryUser() const {
 
   memory_->lock();
   InstancesInfo *inst = static_cast<InstancesInfo*>(memory_->data());
diff --git a/3rdparty/singleapplication/singleapplication_p.h b/3rdparty/singleapplication/singleapplication_p.h
index bf9ae8ad..4893e1e0 100644
--- a/3rdparty/singleapplication/singleapplication_p.h
+++ b/3rdparty/singleapplication/singleapplication_p.h
@@ -86,9 +86,9 @@ class SingleApplicationPrivate : public QObject {
   void startPrimary();
   void startSecondary();
   bool connectToPrimary(const int timeout, const ConnectionType connectionType);
-  quint16 blockChecksum();
-  qint64 primaryPid();
-  QString primaryUser();
+  quint16 blockChecksum() const;
+  qint64 primaryPid() const;
+  QString primaryUser() const;
   void readInitMessageHeader(QLocalSocket *socket);
   void readInitMessageBody(QLocalSocket *socket);
   static void randomSleep();
diff --git a/3rdparty/singleapplication/singlecoreapplication.cpp b/3rdparty/singleapplication/singlecoreapplication.cpp
index 2268622f..5ead4cbb 100644
--- a/3rdparty/singleapplication/singlecoreapplication.cpp
+++ b/3rdparty/singleapplication/singlecoreapplication.cpp
@@ -178,7 +178,7 @@ SingleCoreApplication::~SingleCoreApplication() {
  * Checks if the current application instance is primary.
  * @return Returns true if the instance is primary, false otherwise.
  */
-bool SingleCoreApplication::isPrimary() {
+bool SingleCoreApplication::isPrimary() const {
   Q_D(SingleCoreApplication);
   return d->server_ != nullptr;
 }
@@ -187,7 +187,7 @@ bool SingleCoreApplication::isPrimary() {
  * Checks if the current application instance is secondary.
  * @return Returns true if the instance is secondary, false otherwise.
  */
-bool SingleCoreApplication::isSecondary() {
+bool SingleCoreApplication::isSecondary() const {
   Q_D(SingleCoreApplication);
   return d->server_ == nullptr;
 }
@@ -197,7 +197,7 @@ bool SingleCoreApplication::isSecondary() {
  * It is reset when the first (primary) instance of your app starts and only incremented afterwards.
  * @return Returns a unique instance id.
  */
-quint32 SingleCoreApplication::instanceId() {
+quint32 SingleCoreApplication::instanceId() const {
   Q_D(SingleCoreApplication);
   return d->instanceNumber_;
 }
@@ -207,7 +207,7 @@ quint32 SingleCoreApplication::instanceId() {
  * Especially useful when SingleCoreApplication is coupled with OS. specific APIs.
  * @return Returns the primary instance PID.
  */
-qint64 SingleCoreApplication::primaryPid() {
+qint64 SingleCoreApplication::primaryPid() const {
   Q_D(SingleCoreApplication);
   return d->primaryPid();
 }
@@ -216,7 +216,7 @@ qint64 SingleCoreApplication::primaryPid() {
  * Returns the username the primary instance is running as.
  * @return Returns the username the primary instance is running as.
  */
-QString SingleCoreApplication::primaryUser() {
+QString SingleCoreApplication::primaryUser() const {
   Q_D(SingleCoreApplication);
   return d->primaryUser();
 }
@@ -225,7 +225,7 @@ QString SingleCoreApplication::primaryUser() {
  * Returns the username the current instance is running as.
  * @return Returns the username the current instance is running as.
  */
-QString SingleCoreApplication::currentUser() {
+QString SingleCoreApplication::currentUser() const {
   Q_D(SingleCoreApplication);
   return d->getUsername();
 }
diff --git a/3rdparty/singleapplication/singlecoreapplication.h b/3rdparty/singleapplication/singlecoreapplication.h
index 670f1a41..18470dd4 100644
--- a/3rdparty/singleapplication/singlecoreapplication.h
+++ b/3rdparty/singleapplication/singlecoreapplication.h
@@ -96,37 +96,37 @@ class SingleCoreApplication : public QCoreApplication {
    * @brief Returns if the instance is the primary instance
    * @returns {bool}
    */
-  bool isPrimary();
+  bool isPrimary() const;
 
   /**
    * @brief Returns if the instance is a secondary instance
    * @returns {bool}
    */
-  bool isSecondary();
+  bool isSecondary() const;
 
   /**
    * @brief Returns a unique identifier for the current instance
    * @returns {qint32}
    */
-  quint32 instanceId();
+  quint32 instanceId() const;
 
   /**
    * @brief Returns the process ID (PID) of the primary instance
    * @returns {qint64}
    */
-  qint64 primaryPid();
+  qint64 primaryPid() const;
 
   /**
    * @brief Returns the username of the user running the primary instance
    * @returns {QString}
    */
-  QString primaryUser();
+  QString primaryUser() const;
 
   /**
    * @brief Returns the username of the current user
    * @returns {QString}
    */
-  QString currentUser();
+  QString currentUser() const;
 
   /**
    * @brief Sends a message to the primary instance. Returns true on success.
diff --git a/3rdparty/singleapplication/singlecoreapplication_p.cpp b/3rdparty/singleapplication/singlecoreapplication_p.cpp
index 82fc7397..f2c0c7a6 100644
--- a/3rdparty/singleapplication/singlecoreapplication_p.cpp
+++ b/3rdparty/singleapplication/singlecoreapplication_p.cpp
@@ -284,7 +284,7 @@ bool SingleCoreApplicationPrivate::connectToPrimary(const int timeout, const Con
 
 }
 
-quint16 SingleCoreApplicationPrivate::blockChecksum() {
+quint16 SingleCoreApplicationPrivate::blockChecksum() const {
 
 #if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
   quint16 checksum = qChecksum(QByteArray(static_cast<const char*>(memory_->constData()), offsetof(InstancesInfo, checksum)));
@@ -296,7 +296,7 @@ quint16 SingleCoreApplicationPrivate::blockChecksum() {
 
 }
 
-qint64 SingleCoreApplicationPrivate::primaryPid() {
+qint64 SingleCoreApplicationPrivate::primaryPid() const {
 
   memory_->lock();
   InstancesInfo *inst = static_cast<InstancesInfo*>(memory_->data());
@@ -307,7 +307,7 @@ qint64 SingleCoreApplicationPrivate::primaryPid() {
 
 }
 
-QString SingleCoreApplicationPrivate::primaryUser() {
+QString SingleCoreApplicationPrivate::primaryUser() const {
 
   memory_->lock();
   InstancesInfo *inst = static_cast<InstancesInfo*>(memory_->data());
diff --git a/3rdparty/singleapplication/singlecoreapplication_p.h b/3rdparty/singleapplication/singlecoreapplication_p.h
index 797dc2be..cf3f7dd5 100644
--- a/3rdparty/singleapplication/singlecoreapplication_p.h
+++ b/3rdparty/singleapplication/singlecoreapplication_p.h
@@ -86,9 +86,9 @@ class SingleCoreApplicationPrivate : public QObject {
   void startPrimary();
   void startSecondary();
   bool connectToPrimary(const int timeout, const ConnectionType connectionType);
-  quint16 blockChecksum();
-  qint64 primaryPid();
-  QString primaryUser();
+  quint16 blockChecksum() const;
+  qint64 primaryPid() const;
+  QString primaryUser() const;
   void readInitMessageHeader(QLocalSocket *socket);
   void readInitMessageBody(QLocalSocket *socket);
   static void randomSleep();
diff --git a/src/analyzer/fht.cpp b/src/analyzer/fht.cpp
index 59a62a0c..885c442b 100644
--- a/src/analyzer/fht.cpp
+++ b/src/analyzer/fht.cpp
@@ -58,11 +58,11 @@ void FHT::makeCasTable(void) {
   }
 }
 
-void FHT::scale(float *p, float d) {
+void FHT::scale(float *p, float d) const {
   for (int i = 0; i < (num_ / 2); i++) *p++ *= d;
 }
 
-void FHT::ewma(float *d, float *s, float w) {
+void FHT::ewma(float *d, float *s, float w) const {
   for (int i = 0; i < (num_ / 2); i++, d++, s++) *d = *d * w + *s * (1 - w);
 }
 
diff --git a/src/analyzer/fht.h b/src/analyzer/fht.h
index 0890301d..82bff0b6 100644
--- a/src/analyzer/fht.h
+++ b/src/analyzer/fht.h
@@ -68,7 +68,7 @@ class FHT {
   ~FHT();
   int sizeExp() const;
   int size() const;
-  void scale(float*, float);
+  void scale(float*, float) const;
 
   /**
    * Exponentially Weighted Moving Average (EWMA) filter.
@@ -76,7 +76,7 @@ class FHT {
    * @param s is fresh input.
    * @param w is the weighting factor.
    */
-  void ewma(float *d, float *s, float w);
+  void ewma(float *d, float *s, float w) const;
 
   /**
    * Logarithmic audio spectrum. Maps semi-logarithmic spectrum
diff --git a/src/collection/collectionquery.cpp b/src/collection/collectionquery.cpp
index 447eaa0c..8d04c181 100644
--- a/src/collection/collectionquery.cpp
+++ b/src/collection/collectionquery.cpp
@@ -121,7 +121,7 @@ CollectionQuery::CollectionQuery(const QSqlDatabase &db, const QString &songs_ta
 
 }
 
-QString CollectionQuery::GetInnerQuery() {
+QString CollectionQuery::GetInnerQuery() const {
   return duplicates_only_
              ? QString(" INNER JOIN (select * from duplicated_songs) dsongs        "
                    "ON (%songs_table.artist = dsongs.dup_artist       "
diff --git a/src/collection/collectionquery.h b/src/collection/collectionquery.h
index a995276d..a6bdee10 100644
--- a/src/collection/collectionquery.h
+++ b/src/collection/collectionquery.h
@@ -107,7 +107,7 @@ class CollectionQuery : public QSqlQuery {
   int limit() const { return limit_; }
 
  private:
-  QString GetInnerQuery();
+  QString GetInnerQuery() const;
 
   QSqlDatabase db_;
   QString songs_table_;
diff --git a/src/collection/collectionview.cpp b/src/collection/collectionview.cpp
index dc164c7d..7571d52b 100644
--- a/src/collection/collectionview.cpp
+++ b/src/collection/collectionview.cpp
@@ -636,7 +636,7 @@ void CollectionView::FilterReturnPressed() {
   emit doubleClicked(currentIndex());
 }
 
-void CollectionView::ShowInBrowser() {
+void CollectionView::ShowInBrowser() const {
 
   SongList songs = GetSelectedSongs();
   QList<QUrl> urls;
@@ -649,13 +649,13 @@ void CollectionView::ShowInBrowser() {
 
 }
 
-int CollectionView::TotalSongs() {
+int CollectionView::TotalSongs() const {
   return total_song_count_;
 }
-int CollectionView::TotalArtists() {
+int CollectionView::TotalArtists() const {
   return total_artist_count_;
 }
-int CollectionView::TotalAlbums() {
+int CollectionView::TotalAlbums() const {
   return total_album_count_;
 }
 
diff --git a/src/collection/collectionview.h b/src/collection/collectionview.h
index 04c7bfc1..848244d1 100644
--- a/src/collection/collectionview.h
+++ b/src/collection/collectionview.h
@@ -66,9 +66,9 @@ class CollectionView : public AutoExpandingTreeView {
   void keyboardSearch(const QString &search) override;
   void scrollTo(const QModelIndex &idx, ScrollHint hint = EnsureVisible) override;
 
-  int TotalSongs();
-  int TotalArtists();
-  int TotalAlbums();
+  int TotalSongs() const;
+  int TotalArtists() const;
+  int TotalAlbums() const;
 
  public slots:
   void TotalSongCountUpdated(const int count);
@@ -107,7 +107,7 @@ class CollectionView : public AutoExpandingTreeView {
   void CopyToDevice();
   void EditTracks();
   void RescanSongs();
-  void ShowInBrowser();
+  void ShowInBrowser() const;
   void ShowInVarious();
   void NoShowInVarious();
   void Delete();
diff --git a/src/collection/collectionviewcontainer.cpp b/src/collection/collectionviewcontainer.cpp
index 7ea50ebf..b255f8e0 100644
--- a/src/collection/collectionviewcontainer.cpp
+++ b/src/collection/collectionviewcontainer.cpp
@@ -46,7 +46,7 @@ CollectionViewContainer::CollectionViewContainer(QWidget *parent) : QWidget(pare
 CollectionViewContainer::~CollectionViewContainer() { delete ui_; }
 CollectionView *CollectionViewContainer::view() const { return ui_->view; }
 CollectionFilterWidget *CollectionViewContainer::filter() const { return ui_->filter; }
-void CollectionViewContainer::ReloadSettings() {
+void CollectionViewContainer::ReloadSettings() const {
   filter()->ReloadSettings();
   view()->ReloadSettings();
 }
diff --git a/src/collection/collectionviewcontainer.h b/src/collection/collectionviewcontainer.h
index f5402578..9afda56f 100644
--- a/src/collection/collectionviewcontainer.h
+++ b/src/collection/collectionviewcontainer.h
@@ -41,7 +41,7 @@ class CollectionViewContainer : public QWidget {
   CollectionFilterWidget *filter() const;
   CollectionView *view() const;
 
-  void ReloadSettings();
+  void ReloadSettings() const;
 
  private:
   Ui_CollectionViewContainer *ui_;
diff --git a/src/context/contextalbumsview.cpp b/src/context/contextalbumsview.cpp
index 5cbf8d09..cd60f898 100644
--- a/src/context/contextalbumsview.cpp
+++ b/src/context/contextalbumsview.cpp
@@ -418,7 +418,7 @@ void ContextAlbumsView::CopyToDevice() {
 #endif
 }
 
-void ContextAlbumsView::ShowInBrowser() {
+void ContextAlbumsView::ShowInBrowser() const {
 
   const SongList songs = GetSelectedSongs();
   QList<QUrl> urls;
diff --git a/src/context/contextalbumsview.h b/src/context/contextalbumsview.h
index 8e279f95..94e49b93 100644
--- a/src/context/contextalbumsview.h
+++ b/src/context/contextalbumsview.h
@@ -96,7 +96,7 @@ class ContextAlbumsView : public AutoExpandingTreeView {
   void Organize();
   void CopyToDevice();
   void EditTracks();
-  void ShowInBrowser();
+  void ShowInBrowser() const;
 
  private:
   void RecheckIsEmpty();
diff --git a/src/internet/internetcollectionview.cpp b/src/internet/internetcollectionview.cpp
index ffbe0501..a503a0af 100644
--- a/src/internet/internetcollectionview.cpp
+++ b/src/internet/internetcollectionview.cpp
@@ -440,12 +440,12 @@ void InternetCollectionView::FilterReturnPressed() {
 
 }
 
-int InternetCollectionView::TotalSongs() {
+int InternetCollectionView::TotalSongs() const {
   return total_song_count_;
 }
-int InternetCollectionView::TotalArtists() {
+int InternetCollectionView::TotalArtists() const {
   return total_artist_count_;
 }
-int InternetCollectionView::TotalAlbums() {
+int InternetCollectionView::TotalAlbums() const {
   return total_album_count_;
 }
diff --git a/src/internet/internetcollectionview.h b/src/internet/internetcollectionview.h
index e16fd567..526f158a 100644
--- a/src/internet/internetcollectionview.h
+++ b/src/internet/internetcollectionview.h
@@ -65,9 +65,9 @@ class InternetCollectionView : public AutoExpandingTreeView {
   void keyboardSearch(const QString &search) override;
   void scrollTo(const QModelIndex &idx, ScrollHint hint = EnsureVisible) override;
 
-  int TotalSongs();
-  int TotalArtists();
-  int TotalAlbums();
+  int TotalSongs() const;
+  int TotalArtists() const;
+  int TotalAlbums() const;
 
  public slots:
   void TotalSongCountUpdated(int count);
diff --git a/src/internet/internetcollectionviewcontainer.cpp b/src/internet/internetcollectionviewcontainer.cpp
index cf13ef0d..b560e977 100644
--- a/src/internet/internetcollectionviewcontainer.cpp
+++ b/src/internet/internetcollectionviewcontainer.cpp
@@ -52,7 +52,7 @@ InternetCollectionViewContainer::InternetCollectionViewContainer(QWidget *parent
 
 InternetCollectionViewContainer::~InternetCollectionViewContainer() { delete ui_; }
 
-void InternetCollectionViewContainer::ReloadSettings() {
+void InternetCollectionViewContainer::ReloadSettings() const {
   filter()->ReloadSettings();
   view()->ReloadSettings();
 }
diff --git a/src/internet/internetcollectionviewcontainer.h b/src/internet/internetcollectionviewcontainer.h
index b57ed9b7..5e1e5c35 100644
--- a/src/internet/internetcollectionviewcontainer.h
+++ b/src/internet/internetcollectionviewcontainer.h
@@ -45,7 +45,7 @@ class InternetCollectionViewContainer : public QWidget {
   explicit InternetCollectionViewContainer(QWidget *parent = nullptr);
   ~InternetCollectionViewContainer() override;
 
-  void ReloadSettings();
+  void ReloadSettings() const;
 
   QStackedWidget *stacked() const { return ui_->stacked; }
   QWidget *help_page() const { return ui_->help_page; }
diff --git a/src/playlist/playlistmanager.cpp b/src/playlist/playlistmanager.cpp
index 6e965b01..8e13e4df 100644
--- a/src/playlist/playlistmanager.cpp
+++ b/src/playlist/playlistmanager.cpp
@@ -543,7 +543,7 @@ void PlaylistManager::RemoveItemsWithoutUndo(const int id, const QList<int> &ind
 
 }
 
-void PlaylistManager::RemoveCurrentSong() {
+void PlaylistManager::RemoveCurrentSong() const {
   active()->removeRows(active()->current_index().row(), 1);
 }
 
diff --git a/src/playlist/playlistmanager.h b/src/playlist/playlistmanager.h
index 58286fd6..4ec10bb2 100644
--- a/src/playlist/playlistmanager.h
+++ b/src/playlist/playlistmanager.h
@@ -213,7 +213,7 @@ class PlaylistManager : public PlaylistManagerInterface {
   // Removes items with given indices from the playlist. This operation is not undoable.
   void RemoveItemsWithoutUndo(const int id, const QList<int> &indices);
   // Remove the current playing song
-  void RemoveCurrentSong();
+  void RemoveCurrentSong() const;
 
   void PlaySmartPlaylist(PlaylistGeneratorPtr generator, const bool as_new, const bool clear) override;
 
diff --git a/src/settings/coverssettingspage.cpp b/src/settings/coverssettingspage.cpp
index a8c7acfd..44351c98 100644
--- a/src/settings/coverssettingspage.cpp
+++ b/src/settings/coverssettingspage.cpp
@@ -206,7 +206,7 @@ void CoversSettingsPage::DisableAuthentication() {
 
 }
 
-void CoversSettingsPage::DisconnectAuthentication(CoverProvider *provider) {
+void CoversSettingsPage::DisconnectAuthentication(CoverProvider *provider) const {
 
   QObject::disconnect(provider, &CoverProvider::AuthenticationFailure, this, &CoversSettingsPage::AuthenticationFailure);
   QObject::disconnect(provider, &CoverProvider::AuthenticationSuccess, this, &CoversSettingsPage::AuthenticationSuccess);
diff --git a/src/settings/coverssettingspage.h b/src/settings/coverssettingspage.h
index e41bcd8d..adec3e67 100644
--- a/src/settings/coverssettingspage.h
+++ b/src/settings/coverssettingspage.h
@@ -50,7 +50,7 @@ class CoversSettingsPage : public SettingsPage {
   void NoProviderSelected();
   void ProvidersMove(const int d);
   void DisableAuthentication();
-  void DisconnectAuthentication(CoverProvider *provider);
+  void DisconnectAuthentication(CoverProvider *provider) const;
   static bool ProviderCompareOrder(CoverProvider *a, CoverProvider *b);
 
  private slots:
diff --git a/src/settings/lyricssettingspage.cpp b/src/settings/lyricssettingspage.cpp
index 1fb142f7..e66c0f1d 100644
--- a/src/settings/lyricssettingspage.cpp
+++ b/src/settings/lyricssettingspage.cpp
@@ -196,7 +196,7 @@ void LyricsSettingsPage::DisableAuthentication() {
 
 }
 
-void LyricsSettingsPage::DisconnectAuthentication(LyricsProvider *provider) {
+void LyricsSettingsPage::DisconnectAuthentication(LyricsProvider *provider) const {
 
   QObject::disconnect(provider, &LyricsProvider::AuthenticationFailure, this, &LyricsSettingsPage::AuthenticationFailure);
   QObject::disconnect(provider, &LyricsProvider::AuthenticationSuccess, this, &LyricsSettingsPage::AuthenticationSuccess);
diff --git a/src/settings/lyricssettingspage.h b/src/settings/lyricssettingspage.h
index 2a358e10..ff6ec75f 100644
--- a/src/settings/lyricssettingspage.h
+++ b/src/settings/lyricssettingspage.h
@@ -50,7 +50,7 @@ class LyricsSettingsPage : public SettingsPage {
   void NoProviderSelected();
   void ProvidersMove(const int d);
   void DisableAuthentication();
-  void DisconnectAuthentication(LyricsProvider *provider);
+  void DisconnectAuthentication(LyricsProvider *provider) const;
   static bool ProviderCompareOrder(LyricsProvider *a, LyricsProvider *b);
 
  private slots:
diff --git a/src/subsonic/subsonicbaserequest.cpp b/src/subsonic/subsonicbaserequest.cpp
index a364ad93..ff2247a3 100644
--- a/src/subsonic/subsonicbaserequest.cpp
+++ b/src/subsonic/subsonicbaserequest.cpp
@@ -53,7 +53,7 @@ SubsonicBaseRequest::SubsonicBaseRequest(SubsonicService *service, QObject *pare
 
 }
 
-QUrl SubsonicBaseRequest::CreateUrl(const QString &ressource_name, const QList<Param> &params_provided) {
+QUrl SubsonicBaseRequest::CreateUrl(const QString &ressource_name, const QList<Param> &params_provided) const {
 
   ParamList params = ParamList() << params_provided
                                  << Param("c", client_name())
diff --git a/src/subsonic/subsonicbaserequest.h b/src/subsonic/subsonicbaserequest.h
index 9fca8a2d..afd91cb2 100644
--- a/src/subsonic/subsonicbaserequest.h
+++ b/src/subsonic/subsonicbaserequest.h
@@ -53,7 +53,7 @@ class SubsonicBaseRequest : public QObject {
   typedef QPair<QByteArray, QByteArray> EncodedParam;
   typedef QList<EncodedParam> EncodedParamList;
 
-  QUrl CreateUrl(const QString &ressource_name, const QList<Param> &params_provided);
+  QUrl CreateUrl(const QString &ressource_name, const QList<Param> &params_provided) const;
   QNetworkReply *CreateGetRequest(const QString &ressource_name, const QList<Param> &params_provided);
   QByteArray GetReplyData(QNetworkReply *reply);
   QJsonObject ExtractJsonObj(QByteArray &data);
diff --git a/src/transcoder/transcoder.cpp b/src/transcoder/transcoder.cpp
index 0c9a1bf9..8a6da347 100644
--- a/src/transcoder/transcoder.cpp
+++ b/src/transcoder/transcoder.cpp
@@ -394,7 +394,7 @@ GstBusSyncReply Transcoder::BusCallbackSync(GstBus*, GstMessage *msg, gpointer d
 
 }
 
-void Transcoder::JobState::ReportError(GstMessage *msg) {
+void Transcoder::JobState::ReportError(GstMessage *msg) const {
 
   GError *error = nullptr;
   gchar *debugs = nullptr;
diff --git a/src/transcoder/transcoder.h b/src/transcoder/transcoder.h
index c4458780..ab67255e 100644
--- a/src/transcoder/transcoder.h
+++ b/src/transcoder/transcoder.h
@@ -100,7 +100,7 @@ class Transcoder : public QObject {
     ~JobState();
 
     void PostFinished(const bool success);
-    void ReportError(GstMessage *msg);
+    void ReportError(GstMessage *msg) const;
 
     Job job_;
     Transcoder *parent_;
diff --git a/src/widgets/fancytabwidget.cpp b/src/widgets/fancytabwidget.cpp
index 98bde7ea..81723b78 100644
--- a/src/widgets/fancytabwidget.cpp
+++ b/src/widgets/fancytabwidget.cpp
@@ -360,12 +360,12 @@ class TabData : public QObject {  // clazy:exclude=missing-qobject-macro
     page_->setLayout(layout);
   }
 
-  QWidget *widget_view() { return widget_view_; }
-  QString name() { return name_; }
-  QIcon icon() { return icon_; }
-  QString label() { return label_; }
-  QWidget *page() { return page_; }
-  int index() { return index_; }
+  QWidget *widget_view() const { return widget_view_; }
+  QString name() const { return name_; }
+  QIcon icon() const { return icon_; }
+  QString label() const { return label_; }
+  QWidget *page() const { return page_; }
+  int index() const { return index_; }
 
  private:
   QWidget *widget_view_;