diff --git a/src/libs/languageserverprotocol/icontent.h b/src/libs/languageserverprotocol/icontent.h
index 33ef876510b..e689f500722 100644
--- a/src/libs/languageserverprotocol/icontent.h
+++ b/src/libs/languageserverprotocol/icontent.h
@@ -90,8 +90,8 @@ public:
 };
 
 using ResponseHandler = std::function<void(const QByteArray &, QTextCodec *)>;
-using ResponseHandlers = std::function<void(MessageId, const QByteArray &, QTextCodec *)>;
-using MethodHandler = std::function<void(const QString, MessageId, const IContent *)>;
+using ResponseHandlers = std::function<void(const MessageId &, const QByteArray &, QTextCodec *)>;
+using MethodHandler = std::function<void(const QString &, const MessageId &, const IContent *)>;
 
 inline uint qHash(const LanguageServerProtocol::MessageId &id)
 {
diff --git a/src/libs/languageserverprotocol/jsonrpcmessages.cpp b/src/libs/languageserverprotocol/jsonrpcmessages.cpp
index 466477d7404..e7285b8da9e 100644
--- a/src/libs/languageserverprotocol/jsonrpcmessages.cpp
+++ b/src/libs/languageserverprotocol/jsonrpcmessages.cpp
@@ -85,8 +85,8 @@ void JsonRpcMessageHandler::registerMessageProvider(
 void JsonRpcMessageHandler::parseContent(const QByteArray &content,
                                          QTextCodec *codec,
                                          QString &parseError,
-                                         ResponseHandlers responseHandlers,
-                                         MethodHandler methodHandler)
+                                         const ResponseHandlers &responseHandlers,
+                                         const MethodHandler &methodHandler)
 {
     const QJsonObject &jsonObject = toJsonObject(content, codec, parseError);
     if (jsonObject.isEmpty())
diff --git a/src/libs/languageserverprotocol/jsonrpcmessages.h b/src/libs/languageserverprotocol/jsonrpcmessages.h
index f97ed803fc6..00caab62f60 100644
--- a/src/libs/languageserverprotocol/jsonrpcmessages.h
+++ b/src/libs/languageserverprotocol/jsonrpcmessages.h
@@ -76,8 +76,8 @@ public:
     }
     static QByteArray jsonRpcMimeType();
     static void parseContent(const QByteArray &content, QTextCodec *codec, QString &errorMessage,
-                             ResponseHandlers responseHandlers,
-                             MethodHandler methodHandler);
+                             const ResponseHandlers &responseHandlers,
+                             const MethodHandler &methodHandler);
     static QJsonObject toJsonObject(const QByteArray &content, QTextCodec *codec, QString &parseError);
 
 private:
diff --git a/src/plugins/languageclient/client.cpp b/src/plugins/languageclient/client.cpp
index c238ba454a3..9f237ea8072 100644
--- a/src/plugins/languageclient/client.cpp
+++ b/src/plugins/languageclient/client.cpp
@@ -938,10 +938,10 @@ void Client::handleMessage(const BaseMessage &message)
     if (auto handler = m_contentHandler[message.mimeType]) {
         QString parseError;
         handler(message.content, message.codec, parseError,
-                [this](MessageId id, const QByteArray &content, QTextCodec *codec){
+                [this](const MessageId &id, const QByteArray &content, QTextCodec *codec){
                     this->handleResponse(id, content, codec);
                 },
-                [this](const QString &method, MessageId id, const IContent *content){
+                [this](const QString &method, const MessageId &id, const IContent *content){
                     this->handleMethod(method, id, content);
                 });
         if (!parseError.isEmpty())
@@ -1072,7 +1072,7 @@ void Client::handleResponse(const MessageId &id, const QByteArray &content, QTex
         handler(content, codec);
 }
 
-void Client::handleMethod(const QString &method, MessageId id, const IContent *content)
+void Client::handleMethod(const QString &method, const MessageId &id, const IContent *content)
 {
     ErrorHierarchy error;
     auto logError = [&](const JsonObject &content) {
diff --git a/src/plugins/languageclient/client.h b/src/plugins/languageclient/client.h
index d264898474f..9d8d8487ce8 100644
--- a/src/plugins/languageclient/client.h
+++ b/src/plugins/languageclient/client.h
@@ -189,7 +189,7 @@ protected:
 private:
     void handleResponse(const LanguageServerProtocol::MessageId &id, const QByteArray &content,
                         QTextCodec *codec);
-    void handleMethod(const QString &method, LanguageServerProtocol::MessageId id,
+    void handleMethod(const QString &method, const LanguageServerProtocol::MessageId &id,
                       const LanguageServerProtocol::IContent *content);
 
     void handleDiagnostics(const LanguageServerProtocol::PublishDiagnosticsParams &params);