diff --git a/app/src/handlers/confighandler.h b/app/src/handlers/confighandler.h
index ebaa18e14ec99f246c857d38e20fe7884309fe8f..e46ce5bef2b7998f5ed21a891e53ebf6b7403b91 100644
--- a/app/src/handlers/confighandler.h
+++ b/app/src/handlers/confighandler.h
@@ -10,7 +10,7 @@ class ConfigHandler : public QObject
     Q_OBJECT
 
 public:
-    explicit ConfigHandler(QObject *parent = 0);
+    explicit ConfigHandler(QObject *parent = nullptr);
 
 public slots:
     QJsonObject getAppConfigApplication();
diff --git a/app/src/handlers/itemhandler.h b/app/src/handlers/itemhandler.h
index 5f378c4dbc385704a2a7a5c69890b8b585e23f66..a780a7b1e7415c49f5d7de36236293ed7fc5221a 100644
--- a/app/src/handlers/itemhandler.h
+++ b/app/src/handlers/itemhandler.h
@@ -14,7 +14,7 @@ class ItemHandler : public QObject
     Q_OBJECT
 
 public:
-    explicit ItemHandler(ConfigHandler *configHandler, QObject *parent = 0);
+    explicit ItemHandler(ConfigHandler *configHandler, QObject *parent = nullptr);
 
 signals:
     void metadataSetChanged();
diff --git a/app/src/handlers/ocsapihandler.h b/app/src/handlers/ocsapihandler.h
index 4e4d3095e50f985c7c39f392eaccc85bdc719e5a..b208613358b76e15865950fe6a847b5ca3edcbf5 100644
--- a/app/src/handlers/ocsapihandler.h
+++ b/app/src/handlers/ocsapihandler.h
@@ -10,7 +10,7 @@ class OcsApiHandler : public QObject
     Q_OBJECT
 
 public:
-    explicit OcsApiHandler(ConfigHandler *configHandler, QObject *parent = 0);
+    explicit OcsApiHandler(ConfigHandler *configHandler, QObject *parent = nullptr);
 
 public slots:
     bool addProviders(const QString &providerFileUrl);
diff --git a/app/src/handlers/systemhandler.h b/app/src/handlers/systemhandler.h
index f291c8a89551809a8c0c0ab1d573906ff62405e0..3cbb28f70cd4136d0c2626de313301da85facade 100644
--- a/app/src/handlers/systemhandler.h
+++ b/app/src/handlers/systemhandler.h
@@ -7,7 +7,7 @@ class SystemHandler : public QObject
     Q_OBJECT
 
 public:
-    explicit SystemHandler(QObject *parent = 0);
+    explicit SystemHandler(QObject *parent = nullptr);
 
 public slots:
     bool isUnix();
diff --git a/app/src/websockets/websocketserver.h b/app/src/websockets/websocketserver.h
index 6bcebf7c28fb7d6ee4987b04ff3a89ab378f0eff..d0a269520ff65428e8e74ce21a412e5c549de5cc 100644
--- a/app/src/websockets/websocketserver.h
+++ b/app/src/websockets/websocketserver.h
@@ -18,7 +18,7 @@ class WebSocketServer : public QObject
     Q_OBJECT
 
 public:
-    explicit WebSocketServer(ConfigHandler *configHandler, const QString &serverName = "WebSocketServer", quint16 serverPort = 0, QObject *parent = 0);
+    explicit WebSocketServer(ConfigHandler *configHandler, const QString &serverName = "WebSocketServer", quint16 serverPort = 0, QObject *parent = nullptr);
     ~WebSocketServer();
 
 signals: