diff --git a/src/klettresview.h b/src/klettresview.h
index 1e4553f..44cb69c 100644
--- a/src/klettresview.h
+++ b/src/klettresview.h
@@ -1,112 +1,112 @@
 /***************************************************************************
  *   Copyright (C) 2001-2008 by Anne-Marie Mahfouf                              *
  *   annma@kde.org                                             *
  *                                                                         *
  *   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 2 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, write to the                         *
  *   Free Software Foundation, Inc.,                                       *
  *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.             *
  ***************************************************************************/
 
 #ifndef KLETTRESVIEW_H
 #define KLETTRESVIEW_H
 
 #include <KLineEdit>
 
 class QPixmap;
 class QRect;
 class QSvgRenderer;
 class KLettres;
 class KLTheme;
 
 /**
  * This class serves as the view for KLettres.  It holds the GUI for the kid and grown-up looks
  * and has the code to display the letter/syllable and play the sound.
  *
  * @short KLettres View class
  * @author Anne-Marie Mahfouf <annma@kde.org>
  * @version 2.1
  */
 
 
 class KLettresView : public QWidget
 {
     Q_OBJECT
 public:
     /**
      * Default constructor
      */
     explicit KLettresView(KLettres *parent);
 
     /**
      * Destructor
      */
     virtual ~KLettresView();
     /// Enter a letter into the input widget.
-    void  enterLetter(QString letter) { m_letterEdit->setText(letter); }
+    void  enterLetter(const QString &letter) { m_letterEdit->setText(letter); }
 
     ///The timer value i.e. the time for displaying the letters/syllables
     int m_timer;
     ///The index to the random sequence
     int randomInt;
     ///A Klettres object
     KLettres *m_klettres;
     ///The line where the user enters his/her input
     KLineEdit *m_letterEdit;
     ///set the chosen theme
     void setTheme(KLTheme *theme);
 
 protected:
 
     ///If the user hits backpace
     void keyReleaseEvent(QKeyEvent * e) Q_DECL_OVERRIDE;
     ///Cursor position in the line edit
     int m_cursorPos;
     ///Random number that decides on the letter/syllable and sound
     int m_random;
     ///Length of the syllables
     int m_length;
     ///Choose a sound in random and ensure that it's not the same than the previous one
     void chooseSound();
     ///Current letter or syllable stored
     QString m_currentLetter;
     ///Current letter entered uppercase i.e. m_inputLetter.upper()
     QString m_upperLetter;
     ///Paint the letter/syllable in levels 1 and 3 and the background
     void paintEvent( QPaintEvent * ) Q_DECL_OVERRIDE;
     ///Paint the background picture
     void paintBackground(QPainter &p, const QRect& rect);    
     ///Paint the letter/syllable in levels 1 and 3 
     void paintLetter(QPainter &p, const QRect& rect);
     ///Current theme
     KLTheme *m_theme = nullptr;
 
     // Graphics  ----------------
     QSvgRenderer *m_renderer = nullptr;
     QPixmap       m_backgroundCache;
 
 public Q_SLOTS:
     ///Start playing displaying a new letter/syllable, playing the associated sound
     void game();
 
 public Q_SLOTS:
     ///Play the same sound again
     void slotPlayAgain();
 
     void slotProcess(const QString &inputLetter);
 
     void slotTimerDone();
 
 };
 
 #endif // KLETTRESVIEW_H