diff --git a/src/core/synth/GSynth.cpp b/src/core/synth/GSynth.cpp
index 6c8b32c2c..e5fc79abb 100644
--- a/src/core/synth/GSynth.cpp
+++ b/src/core/synth/GSynth.cpp
@@ -1,97 +1,97 @@
 /* GCompris - GSynth.cpp
  *
  * Copyright (C) 2018 Timothée Giet <animtim@gmail.com>
  *
  * Authors:
  *   Johnny Jazeix <jazeix@gmail.com>
  *   Timothée Giet <animtim@gmail.com>
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
  *   the Free Software Foundation; either version 3 of the License, or
  *   (at your option) any later version.
  *
  *   This program is distributed in the hope that it will be useful,
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  *
  *   You should have received a copy of the GNU General Public License
  *   along with this program; if not, see <https://www.gnu.org/licenses/>.
  */
 
 #include "GSynth.h"
 #include "generator.h"
 
 #include <QDebug>
 
 GSynth *GSynth::m_instance = nullptr;
 
 GSynth::GSynth(QObject *parent) : QObject(parent)
 {
-    bufferSize = 8192;
+    static const int bufferSize = 8192;
 
     m_format.setSampleRate(22050);
     m_format.setChannelCount(1);
     m_format.setSampleSize(16);
     m_format.setCodec("audio/pcm");
     m_format.setByteOrder(QAudioFormat::LittleEndian);
     m_format.setSampleType(QAudioFormat::SignedInt);
 
     QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
     if (!info.isFormatSupported(m_format)) {
         qWarning() << "Default format not supported - trying to use nearest";
         m_format = info.nearestFormat(m_format);
     }
     m_device = QAudioDeviceInfo::defaultOutputDevice();
     m_buffer = QByteArray(bufferSize, 0);
 
     m_audioOutput = new QAudioOutput(m_device, m_format, this);
     m_audioOutput->setBufferSize(bufferSize);
     m_generator   = new Generator(m_format, this);
     // todo Only start generator if musical activity, and stop it on exit (in main.qml, activity.isMusicalActivity)
     m_generator->setPreset(PresetCustom);
     m_generator->start();
     m_audioOutput->start(m_generator);
     m_audioOutput->setVolume(1);
 }
 
 GSynth::~GSynth() {
     m_audioOutput->stop();
     m_generator->stop();
     delete m_audioOutput;
     delete m_generator;
     
     auto i = m_timers.constBegin();
     while (i != m_timers.constEnd()) {
         delete i.value();
         ++i;
     }
 }
 
 void GSynth::generate(int note, int duration) {
     //test part...
     m_generator->noteOn(1, note, 255);
     if(!m_timers.contains(note)) {
         m_timers[note] = new QTimer();
         connect(m_timers[note], &QTimer::timeout, this,
                 [this, note]() {
                     stopAudio(note);
                 });
     }
     m_timers[note]->start(duration);
 }
 
 void GSynth::stopAudio(int note) {
     m_generator->noteOff(1, note);
 }
 
 QObject *GSynth::synthProvider(QQmlEngine *engine,
                                QJSEngine *scriptEngine)
 {
     Q_UNUSED(engine)
     Q_UNUSED(scriptEngine)
 
     GSynth* synth = getInstance();
     return synth;
 }
diff --git a/src/core/synth/GSynth.h b/src/core/synth/GSynth.h
index 962e975ed..09fce75ba 100644
--- a/src/core/synth/GSynth.h
+++ b/src/core/synth/GSynth.h
@@ -1,79 +1,77 @@
 /* GCompris - GSynth.h
  *
  * Copyright (C) 2018 Timothée Giet <animtim@gmail.com>
  *
  * Authors:
  *   Johnny Jazeix <jazeix@gmail.com>
  *   Timothée Giet <animtim@gmail.com>
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
  *   the Free Software Foundation; either version 3 of the License, or
  *   (at your option) any later version.
  *
  *   This program is distributed in the hope that it will be useful,
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  *
  *   You should have received a copy of the GNU General Public License
  *   along with this program; if not, see <https://www.gnu.org/licenses/>.
  */
 #ifndef GSYNTH_H
 #define GSYNTH_H
 
 #include <QAudioDeviceInfo>
 #include <QAudioOutput>
 #include <QTimer>
 #include <QQmlEngine>
 #include "preset.h"
 
 class Generator;
 
 class GSynth : public QObject
 {
     Q_OBJECT
 
 public:
     explicit GSynth(QObject *parent = 0);
     virtual ~GSynth();
 
     /**
      * Generate a note and start the corresponding timer
      *  to stop it at "duration" ms.
      *
      * @param note note to play
      * @param duration how much time the note needs to be played
      */
     Q_INVOKABLE void generate(int note, int duration);
 
     static GSynth *getInstance() {
         if(!m_instance) {
             m_instance = new GSynth();
         }
         return m_instance;
     }
     static QObject *synthProvider(QQmlEngine *engine,
                                   QJSEngine *scriptEngine);
 
 protected:
     static GSynth *m_instance;
 
 private slots:
     void stopAudio(int note);
     
 private:
-    unsigned int bufferSize;
-
     Generator        *m_generator;
     QAudioDeviceInfo  m_device;
     QAudioFormat      m_format;
     QByteArray        m_buffer;
     QAudioOutput     *m_audioOutput;
     QMap<int, QTimer *> m_timers;
     
     Preset PresetCustom;
 };
 
 #endif // GSYNTH_H