diff --git a/Modules/IGT/IO/mitkNavigationDataPlayerBase.h b/Modules/IGT/IO/mitkNavigationDataPlayerBase.h
index 401de6723e..d79419f6bc 100644
--- a/Modules/IGT/IO/mitkNavigationDataPlayerBase.h
+++ b/Modules/IGT/IO/mitkNavigationDataPlayerBase.h
@@ -1,118 +1,118 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #ifndef MITKNavigationDataPlayerBase_H_HEADER_INCLUDED_
 #define MITKNavigationDataPlayerBase_H_HEADER_INCLUDED_
 
 #include "mitkNavigationDataSource.h"
 #include "mitkNavigationDataSet.h"
 
 namespace mitk{
   /**
   * \brief Base class for using mitk::NavigationData as a filter source.
   * Subclasses can play objects of mitk::NavigationDataSet.
   *
   * Each subclass has to check the state of m_Repeat and do or do not repeat
   * the playing accordingly.
   *
   * \ingroup IGT
   */
   class MITKIGT_EXPORT NavigationDataPlayerBase
     : public NavigationDataSource
   {
   public:
     mitkClassMacro(NavigationDataPlayerBase, NavigationDataSource)
 
     /**
     * \brief Set to true if the data player should repeat the outputs.
     */
     itkSetMacro(Repeat, bool)
 
     /**
     * \return Returns if the data player should repeat the outputs.
     */
     itkGetMacro(Repeat, bool)
 
     /**
     * \brief Used for pipeline update just to tell the pipeline that we always have to update.
     */
     virtual void UpdateOutputInformation() override;
 
     itkGetMacro(NavigationDataSet, NavigationDataSet::Pointer)
 
     /**
     * \brief Set mitk::NavigationDataSet for playing.
     * Player is initialized by call to mitk::NavigationDataPlayerBase::InitPlayer()
     * inside this method. Method must be called before this object can be used as
     * a filter source.
     *
     * @param navigationDataSet mitk::NavigationDataSet which will be played by this player.
     */
     void SetNavigationDataSet(NavigationDataSet::Pointer navigationDataSet);
 
     /**
     * \brief Getter for the size of the mitk::NavigationDataSet used in this object.
     *
     * @return Returns the number of navigation data snapshots available in the player.
     */
     unsigned int GetNumberOfSnapshots();
 
     unsigned int GetCurrentSnapshotNumber();
 
     /**
     * \brief This method checks if player arrived at end of file.
     *
     * @return true if last mitk::NavigationData object is in the outputs, false otherwise
     */
     bool IsAtEnd();
 
   protected:
     NavigationDataPlayerBase();
     virtual ~NavigationDataPlayerBase();
 
     /**
     * \brief Every subclass hast to implement this method. See ITK filter documentation for details.
     */
     virtual void GenerateData() = 0;
 
     /**
     * \brief Initializes the outputs of this NavigationDataSource.
     * Aftwer calling this method, the first Navigationdata from the loaded Navigationdataset is loaded into the outputs.
     */
     void InitPlayer();
 
     /**
     * \brief Convenience method for subclasses.
     * When there are no further mitk::NavigationData objects available, this
     * method can be called in the implementation of mitk::NavigationDataPlayerBase::GenerateData().
     */
     void GraftEmptyOutput();
 
     /**
     * \brief If the player should repeat outputs. Default is false.
     */
     bool m_Repeat;
 
     NavigationDataSet::Pointer m_NavigationDataSet;
 
     /**
     * \brief Iterator always points to the NavigationData object which is in the outputs at the moment.
     */
-    mitk::NavigationDataSet::NavigationDataSetIterator m_NavigationDataSetIterator;
+    mitk::NavigationDataSet::NavigationDataSetConstIterator m_NavigationDataSetIterator;
   };
 } // namespace mitk
 
 #endif /* MITKNavigationDataSequentialPlayer_H_HEADER_INCLUDED_ */