diff --git a/src/demoreader.h b/src/demoreader.h
--- a/src/demoreader.h
+++ b/src/demoreader.h
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2017 Hasan Yavuz Özderya
+  Copyright © 2018 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -38,13 +38,12 @@ class DemoReader : public AbstractReader
     Q_OBJECT
 
 public:
-    explicit DemoReader(QIODevice* device, ChannelManager* channelMan,
-                        DataRecorder* recorder, QObject* parent = 0);
+    explicit DemoReader(QIODevice* device, QObject* parent = 0);
 
     /// Demo reader is an exception so this function returns NULL
     QWidget* settingsWidget();
 
-    unsigned numOfChannels();
+    unsigned numChannels() const;
 
     void enable(bool enabled = true);
 
@@ -56,7 +55,7 @@ public slots:
 
 private:
     bool paused;
-    unsigned _numOfChannels;
+    unsigned _numChannels;
     QTimer timer;
     int count;