diff --git a/src/lyrics/auddlyricsprovider.cpp b/src/lyrics/auddlyricsprovider.cpp
index 83cd5c7fd..2b8d254f1 100644
--- a/src/lyrics/auddlyricsprovider.cpp
+++ b/src/lyrics/auddlyricsprovider.cpp
@@ -53,7 +53,7 @@ const int AuddLyricsProvider::kMaxLength = 6000;
 
 AuddLyricsProvider::AuddLyricsProvider(QObject *parent) : LyricsProvider("AudD", parent), network_(new NetworkAccessManager(this)) {}
 
-bool AuddLyricsProvider::StartSearch(const QString &artist, const QString &album, const QString &title, quint64 id) {
+bool AuddLyricsProvider::StartSearch(const QString &artist, const QString &album, const QString &title, const quint64 id) {
 
   const ParamList params = ParamList() << Param("api_token", QByteArray::fromBase64(kAPITokenB64))
                                        << Param("q", QString(artist + " " + title));
@@ -66,7 +66,7 @@ bool AuddLyricsProvider::StartSearch(const QString &artist, const QString &album
   QUrl url(kUrlSearch);
   url.setQuery(url_query);
   QNetworkReply *reply = network_->get(QNetworkRequest(url));
-  NewClosure(reply, SIGNAL(finished()), this, SLOT(HandleSearchReply(QNetworkReply*, quint64, QString, QString)), reply, id, artist, title);
+  NewClosure(reply, SIGNAL(finished()), this, SLOT(HandleSearchReply(QNetworkReply*, const quint64, const QString&, const QString&)), reply, id, artist, title);
 
   //qLog(Debug) << "AudDLyrics: Sending request for" << url;
 
@@ -77,7 +77,7 @@ bool AuddLyricsProvider::StartSearch(const QString &artist, const QString &album
 void AuddLyricsProvider::CancelSearch(quint64 id) {
 }
 
-void AuddLyricsProvider::HandleSearchReply(QNetworkReply *reply, quint64 id, const QString artist, const QString title) {
+void AuddLyricsProvider::HandleSearchReply(QNetworkReply *reply, const quint64 id, const QString &artist, const QString &title) {
 
   reply->deleteLater();
 
@@ -127,7 +127,7 @@ void AuddLyricsProvider::HandleSearchReply(QNetworkReply *reply, quint64 id, con
 
 }
 
-QJsonObject AuddLyricsProvider::ExtractJsonObj(QNetworkReply *reply, quint64 id) {
+QJsonObject AuddLyricsProvider::ExtractJsonObj(QNetworkReply *reply, const quint64 id) {
 
   if (reply->error() != QNetworkReply::NoError) {
     QString failure_reason = QString("%1 (%2)").arg(reply->errorString()).arg(reply->error());
@@ -206,7 +206,7 @@ QJsonArray AuddLyricsProvider::ExtractResult(QNetworkReply *reply, const quint64
 
 }
 
-void AuddLyricsProvider::Error(quint64 id, QString error, QVariant debug) {
+void AuddLyricsProvider::Error(const quint64 id, const QString &error, QVariant debug) {
   qLog(Error) << "AudDLyrics:" << error;
   if (debug.isValid()) qLog(Debug) << debug;
   LyricsSearchResults results;
diff --git a/src/lyrics/auddlyricsprovider.h b/src/lyrics/auddlyricsprovider.h
index 29f293ce0..39dbb03a4 100644
--- a/src/lyrics/auddlyricsprovider.h
+++ b/src/lyrics/auddlyricsprovider.h
@@ -44,16 +44,16 @@ class AuddLyricsProvider : public LyricsProvider {
   void CancelSearch(quint64 id);
 
  private slots:
-  void HandleSearchReply(QNetworkReply *reply, quint64 id, const QString artist, const QString title);
+  void HandleSearchReply(QNetworkReply *reply, const quint64 id, const QString &artist, const QString &title);
 
  private:
   static const char *kUrlSearch;
   static const char *kAPITokenB64;
   static const int kMaxLength;
   QNetworkAccessManager *network_;
-  void Error(quint64 id, QString error, QVariant debug = QVariant());
+  void Error(const quint64 id, const QString &error, QVariant debug = QVariant());
 
-  QJsonObject ExtractJsonObj(QNetworkReply *reply, quint64 id);
+  QJsonObject ExtractJsonObj(QNetworkReply *reply, const quint64 id);
   QJsonArray ExtractResult(QNetworkReply *reply, const quint64 id, const QString &artist, const QString &title);
 
 };
diff --git a/src/lyrics/chartlyricsprovider.cpp b/src/lyrics/chartlyricsprovider.cpp
index d03703728..782b7a1b1 100644
--- a/src/lyrics/chartlyricsprovider.cpp
+++ b/src/lyrics/chartlyricsprovider.cpp
@@ -45,7 +45,7 @@ const int ChartLyricsProvider::kMaxLength = 6000;
 
 ChartLyricsProvider::ChartLyricsProvider(QObject *parent) : LyricsProvider("ChartLyrics", parent), network_(new NetworkAccessManager(this)) {}
 
-bool ChartLyricsProvider::StartSearch(const QString &artist, const QString &album, const QString &title, quint64 id) {
+bool ChartLyricsProvider::StartSearch(const QString &artist, const QString &album, const QString &title, const quint64 id) {
 
   const ParamList params = ParamList() << Param("artist", artist)
                                        << Param("song", title);
@@ -58,7 +58,7 @@ bool ChartLyricsProvider::StartSearch(const QString &artist, const QString &albu
   QUrl url(kUrlSearch);
   url.setQuery(url_query);
   QNetworkReply *reply = network_->get(QNetworkRequest(url));
-  NewClosure(reply, SIGNAL(finished()), this, SLOT(HandleSearchReply(QNetworkReply*, quint64, QString, QString)), reply, id, artist, title);
+  NewClosure(reply, SIGNAL(finished()), this, SLOT(HandleSearchReply(QNetworkReply*, const quint64, const QString&, const QString&)), reply, id, artist, title);
 
   //qLog(Debug) << "ChartLyrics: Sending request for" << url;
 
@@ -66,10 +66,10 @@ bool ChartLyricsProvider::StartSearch(const QString &artist, const QString &albu
 
 }
 
-void ChartLyricsProvider::CancelSearch(quint64 id) {
+void ChartLyricsProvider::CancelSearch(const quint64 id) {
 }
 
-void ChartLyricsProvider::HandleSearchReply(QNetworkReply *reply, quint64 id, const QString artist, const QString title) {
+void ChartLyricsProvider::HandleSearchReply(QNetworkReply *reply, const quint64 id, const QString &artist, const QString &title) {
 
   reply->deleteLater();
 
@@ -122,7 +122,7 @@ void ChartLyricsProvider::HandleSearchReply(QNetworkReply *reply, quint64 id, co
 
 }
 
-void ChartLyricsProvider::Error(quint64 id, QString error, QVariant debug) {
+void ChartLyricsProvider::Error(const quint64 id, const QString &error, QVariant debug) {
   qLog(Error) << "ChartLyrics:" << error;
   if (debug.isValid()) qLog(Debug) << debug;
   LyricsSearchResults results;
diff --git a/src/lyrics/chartlyricsprovider.h b/src/lyrics/chartlyricsprovider.h
index f183aee74..65a4c0436 100644
--- a/src/lyrics/chartlyricsprovider.h
+++ b/src/lyrics/chartlyricsprovider.h
@@ -39,17 +39,17 @@ class ChartLyricsProvider : public LyricsProvider {
  public:
   explicit ChartLyricsProvider(QObject *parent = nullptr);
 
-  bool StartSearch(const QString &artist, const QString &album, const QString &title, quint64 id);
+  bool StartSearch(const QString &artist, const QString &album, const QString &title, const quint64 id);
   void CancelSearch(quint64 id);
 
  private slots:
-  void HandleSearchReply(QNetworkReply *reply, quint64 id, const QString artist, const QString title);
+  void HandleSearchReply(QNetworkReply *reply, const quint64 id, const QString &artist, const QString &title);
 
  private:
   static const char *kUrlSearch;
   static const int kMaxLength;
   QNetworkAccessManager *network_;
-  void Error(quint64 id, QString error, QVariant debug = QVariant());
+  void Error(const quint64 id, const QString &error, QVariant debug = QVariant());
 
 };
 
diff --git a/src/lyrics/lyricsfetcher.cpp b/src/lyrics/lyricsfetcher.cpp
index 6e38e6da1..9c4dae438 100644
--- a/src/lyrics/lyricsfetcher.cpp
+++ b/src/lyrics/lyricsfetcher.cpp
@@ -94,7 +94,7 @@ void LyricsFetcher::StartRequests() {
     LyricsFetcherSearch *search = new LyricsFetcherSearch(request, this);
     active_requests_.insert(request.id, search);
 
-    connect(search, SIGNAL(SearchFinished(const quint64, LyricsSearchResults)), SLOT(SingleSearchFinished(const quint64, LyricsSearchResults)));
+    connect(search, SIGNAL(SearchFinished(const quint64, const LyricsSearchResults&)), SLOT(SingleSearchFinished(const quint64, const LyricsSearchResults&)));
     connect(search, SIGNAL(LyricsFetched(const quint64, const QString&, const QString&)), SLOT(SingleLyricsFetched(const quint64, const QString&, const QString&)));
 
     search->Start(lyrics_providers_);
@@ -102,7 +102,7 @@ void LyricsFetcher::StartRequests() {
 
 }
 
-void LyricsFetcher::SingleSearchFinished(const quint64 request_id, LyricsSearchResults results) {
+void LyricsFetcher::SingleSearchFinished(const quint64 request_id, const LyricsSearchResults &results) {
 
   LyricsFetcherSearch *search = active_requests_.take(request_id);
   if (!search) return;
diff --git a/src/lyrics/lyricsfetcher.h b/src/lyrics/lyricsfetcher.h
index 763ff0cd1..860a5e2e0 100644
--- a/src/lyrics/lyricsfetcher.h
+++ b/src/lyrics/lyricsfetcher.h
@@ -73,7 +73,7 @@ signals:
   void SearchFinished(const quint64 request_id, const LyricsSearchResults &results);
 
  private slots:
-  void SingleSearchFinished(const quint64 request_id, LyricsSearchResults results);
+  void SingleSearchFinished(const quint64 request_id, const LyricsSearchResults &results);
   void SingleLyricsFetched(const quint64 request_id, const QString &provider, const QString &lyrics);
   void StartRequests();
 
diff --git a/src/lyrics/lyricsfetchersearch.cpp b/src/lyrics/lyricsfetchersearch.cpp
index 8ee027af4..33465da1b 100644
--- a/src/lyrics/lyricsfetchersearch.cpp
+++ b/src/lyrics/lyricsfetchersearch.cpp
@@ -59,7 +59,7 @@ void LyricsFetcherSearch::TerminateSearch() {
 void LyricsFetcherSearch::Start(LyricsProviders *lyrics_providers) {
 
   for (LyricsProvider *provider : lyrics_providers->List()) {
-    connect(provider, SIGNAL(SearchFinished(const quint64, QList<LyricsSearchResult>)), SLOT(ProviderSearchFinished(const quint64, QList<LyricsSearchResult>)));
+    connect(provider, SIGNAL(SearchFinished(const quint64, const LyricsSearchResults&)), SLOT(ProviderSearchFinished(const quint64, const LyricsSearchResults&)));
     const int id = lyrics_providers->NextId();
     const bool success = provider->StartSearch(request_.artist, request_.album, request_.title, id);
     if (success) pending_requests_[id] = provider;
@@ -69,7 +69,7 @@ void LyricsFetcherSearch::Start(LyricsProviders *lyrics_providers) {
 
 }
 
-void LyricsFetcherSearch::ProviderSearchFinished(const quint64 id, const QList<LyricsSearchResult> &results) {
+void LyricsFetcherSearch::ProviderSearchFinished(const quint64 id, const LyricsSearchResults &results) {
 
   if (!pending_requests_.contains(id)) return;
   LyricsProvider *provider = pending_requests_.take(id);
diff --git a/src/lyrics/lyricsfetchersearch.h b/src/lyrics/lyricsfetchersearch.h
index 976cab783..6bc112b2a 100644
--- a/src/lyrics/lyricsfetchersearch.h
+++ b/src/lyrics/lyricsfetchersearch.h
@@ -48,7 +48,7 @@ class LyricsFetcherSearch : public QObject {
   void LyricsFetched(const quint64, const QString &provider, const QString &lyrics);
 
  private slots:
-  void ProviderSearchFinished(const quint64 id, const QList<LyricsSearchResult> &results);
+  void ProviderSearchFinished(const quint64 id, const LyricsSearchResults &results);
   void TerminateSearch();
 
  private:
diff --git a/src/lyrics/lyricsprovider.h b/src/lyrics/lyricsprovider.h
index 090e074ec..3fc87c86e 100644
--- a/src/lyrics/lyricsprovider.h
+++ b/src/lyrics/lyricsprovider.h
@@ -28,7 +28,7 @@
 #include <QList>
 #include <QString>
 
-struct LyricsSearchResult;
+#include "lyricsfetcher.h"
 
 class LyricsProvider : public QObject {
   Q_OBJECT
@@ -41,11 +41,11 @@ class LyricsProvider : public QObject {
 
   QString name() const { return name_; }
 
-  virtual bool StartSearch(const QString &artist, const QString &album, const QString &title, quint64 id) = 0;
-  virtual void CancelSearch(quint64 id) {}
+  virtual bool StartSearch(const QString &artist, const QString &album, const QString &title, const quint64 id) = 0;
+  virtual void CancelSearch(const quint64 id) {}
 
  signals:
-  void SearchFinished(quint64 id, const QList<LyricsSearchResult>& results);
+  void SearchFinished(const quint64 id, const LyricsSearchResults &results);
 
  private:
   QString name_;