diff --git a/include/mqttclient.h b/include/mqttclient.h
index 7d9e666..7eaa795 100644
--- a/include/mqttclient.h
+++ b/include/mqttclient.h
@@ -46,20 +46,20 @@ namespace mqtt {
 class Subscription
 {
 public:
-    Subscription( const std::string &topic, int qos, const std::function<void(MqttMessage)>& call_back )
+    Subscription( const std::string &topic, int qos, const std::function<void(MqttMessage)> call_back )
         : m_topic( topic )
         , m_qos( qos )
-        , m_call_back(const_cast<std::function<void(MqttMessage)>&>(call_back ))
+        , m_call_back(call_back )
     {}
 
     std::string     getTopic() const { return m_topic; }
     int             getQoS() const { return m_qos; }
-    std::function<void(MqttMessage)>&  getCallBack() const { return m_call_back; }
+    std::function<void(MqttMessage)>  getCallBack() { return m_call_back; }
 
 private:
     std::string m_topic;
     int         m_qos;
-    std::function<void(MqttMessage)>& m_call_back;
+    std::function<void(MqttMessage)> m_call_back;
 };
 
 // Forward definition
diff --git a/src/mqttclient.cpp b/src/mqttclient.cpp
index d39e536..e1454f4 100644
--- a/src/mqttclient.cpp
+++ b/src/mqttclient.cpp
@@ -256,7 +256,7 @@ Token MqttClient::subscribe(const std::string& topic, int qos, const std::functi
             // Store the subscription in the buffer for later processing.
             {
                 OSDEV_COMPONENTS_LOCKGUARD(m_subscriptionMutex);
-                m_deferredSubscriptions.push_back( Subscription( topic, qos, cb ) );
+                m_deferredSubscriptions.emplace_back( topic, qos, cb );
             }
 
             return Token(m_clientId, -1);
@@ -271,7 +271,8 @@ Token MqttClient::subscribe(const std::string& topic, int qos, const std::functi
         {
             for (const auto& c : m_additionalClients)
             {
-                if (!c->isOverlapping(topic)) {
+                if (!c->isOverlapping(topic))
+                {
                     client = c.get();
                     clientFound = true;
                     break;
@@ -306,13 +307,15 @@ std::set<Token> MqttClient::unsubscribe(const std::string& topic, int qos)
     std::vector<IMqttClientImpl*> clients{};
     {
         OSDEV_COMPONENTS_LOCKGUARD(m_internalMutex);
-        if (!m_principalClient || m_principalClient->connectionStatus() == ConnectionStatus::Disconnected) {
+        if (!m_principalClient || m_principalClient->connectionStatus() == ConnectionStatus::Disconnected)
+        {
             LogError("[MqttClient::unsubscribe]", std::string( m_clientId + " - Unable to unsubscribe, not connected" ) );
             // Throw (MqttException, "Not connected");
             return std::set<Token>();
         }
         clients.push_back(m_principalClient.get());
-        for (const auto& c : m_additionalClients) {
+        for (const auto& c : m_additionalClients)
+        {
             clients.push_back(c.get());
         }
     }