diff --git a/Modules/AlgorithmsExt/include/mitkSimpleHistogram.h b/Modules/AlgorithmsExt/include/mitkSimpleHistogram.h
index 117fb10ff7..f7fb60ae7f 100644
--- a/Modules/AlgorithmsExt/include/mitkSimpleHistogram.h
+++ b/Modules/AlgorithmsExt/include/mitkSimpleHistogram.h
@@ -1,130 +1,130 @@
 /*============================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center (DKFZ)
 All rights reserved.
 
 Use of this source code is governed by a 3-clause BSD license that can be
 found in the LICENSE file.
 
 ============================================================================*/
 
 #ifndef mitkSimpleHistogram_h
 #define mitkSimpleHistogram_h
 
 #ifndef __itkHistogram_h
 #include <itkHistogram.h>
 #endif
 
 #include "MitkAlgorithmsExtExports.h"
 
 #include <mitkImage.h>
 #include <mitkWeakPointer.h>
 
 #include <itkImageRegionIterator.h>
 #include <itkImageRegionIteratorWithIndex.h>
 
 namespace mitk
 {
   //##Documentation
   //## @brief Abstract superclass for histograms with double values.
   //##        Classes which are deriving from this class can be cached
   //##        in the same way.
   class MITKALGORITHMSEXT_EXPORT SimpleHistogram
   {
   public:
     /** @brief Returns the minimal value of the histogram. */
     virtual double GetMin() const = 0;
     /** @brief Returns the maximum value of the histogram. */
     virtual double GetMax() const = 0;
     /** @brief Creates a new histogram out the source. */
     virtual void ComputeFromBaseData(BaseData *source) = 0;
     /** @brief TODO: (What should this method do?)*/
     virtual float GetRelativeBin(double start, double end) const = 0;
   };
 
   class MITKALGORITHMSEXT_EXPORT SimpleImageHistogram : public SimpleHistogram
   {
   public:
     typedef itk::Statistics::Histogram<double> HistogramType;
 
     SimpleImageHistogram()
     {
       valid = false;
     }
 
     ~SimpleImageHistogram()
     {
     }
 
     /** @return Returns if the current histogram is valid, false if not. */
     bool GetValid();
 
     typedef itk::Image<short, 3> CTImage;
     typedef itk::ImageRegionIterator<CTImage> CTIteratorType;
     typedef itk::ImageRegionIteratorWithIndex<CTImage> CTIteratorIndexType;
 
     typedef itk::Image<unsigned char, 3> BinImage;
     typedef itk::ImageRegionIterator<BinImage> BinIteratorType;
     typedef itk::ImageRegionIteratorWithIndex<BinImage> BinIteratorIndexType;
 
     typedef unsigned long CountType;
 
   protected:
     HistogramType::ConstPointer histogram;
 
     bool valid;
-    int nBins = 256;
+    unsigned int nBins = 256;
     double invLogHighest;
 
   public:
     double GetMin() const override;
     double GetMax() const override;
 
     /** @brief Creates a new histogram out the source which must be an image. Method does nothing if the image is
      * invalid, nullptr, etc.. */
     void ComputeFromBaseData(BaseData *source) override;
     float GetRelativeBin(double start, double end) const override;
   };
 
   class MITKALGORITHMSEXT_EXPORT SimpleHistogramCache
   {
   public:
     static const unsigned int maxCacheSize = 64;
 
     class MITKALGORITHMSEXT_EXPORT Element
     {
     public:
       mitk::WeakPointer<BaseData> baseData;
       itk::TimeStamp m_LastUpdateTime;
 
       virtual ~Element();
 
       virtual void ComputeFromBaseData(BaseData *baseData) = 0;
       virtual SimpleHistogram *GetHistogram() = 0;
     };
 
     typedef std::list<Element *> CacheContainer;
 
     CacheContainer cache;
 
     SimpleHistogramCache() {}
     ~SimpleHistogramCache() { TrimCache(true); }
     SimpleHistogram *operator[](BaseData::Pointer sp_BaseData);
 
   protected:
     void TrimCache(bool full = false)
     {
       unsigned int targetSize = full ? 0 : maxCacheSize;
 
       while (cache.size() > targetSize)
       {
         delete cache.back();
         cache.pop_back();
       }
     }
   };
 }
 
 #endif