diff --git a/Modules/Multilabel/Testing/mitkLabelSetTest.cpp b/Modules/Multilabel/Testing/mitkLabelSetTest.cpp
index 26517ef986..d4c71fc23e 100644
--- a/Modules/Multilabel/Testing/mitkLabelSetTest.cpp
+++ b/Modules/Multilabel/Testing/mitkLabelSetTest.cpp
@@ -1,170 +1,170 @@
 /*============================================================================
 
 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.
 
 ============================================================================*/
 
 #include <mitkLabelSet.h>
 #include <mitkLabelSetImage.h>
 #include <mitkStringProperty.h>
 #include <mitkTestFixture.h>
 #include <mitkTestingMacros.h>
 
 class mitkLabelSetTestSuite : public mitk::TestFixture
 {
   CPPUNIT_TEST_SUITE(mitkLabelSetTestSuite);
   MITK_TEST(TestSetLayer);
   MITK_TEST(TestSetActiveLabel);
   MITK_TEST(TestRemoveLabel);
   MITK_TEST(TestAddLabel);
   MITK_TEST(TestRenameLabel);
   MITK_TEST(TestSetAllLabelsVisible);
   MITK_TEST(TestSetAllLabelsLocked);
   MITK_TEST(TestRemoveAllLabels);
   CPPUNIT_TEST_SUITE_END();
 
 private:
   mitk::LabelSet::Pointer m_LabelSet;
   mitk::LabelSet::PixelType m_InitialNumberOfLabels;
 
   void AddLabels(mitk::LabelSet::PixelType numOfLabels)
   {
     mitk::Label::Pointer label;
     const std::string namePrefix = "Label_";
     const mitk::Color gray(0.5f);
 
     for (mitk::Label::PixelType i = 0; i < numOfLabels; ++i)
     {
       label = mitk::Label::New();
       label->SetName(namePrefix + std::to_string(i));
       label->SetValue(i);
       label->SetVisible((i % 2 == 0));
       label->SetLayer(i % 3);
       label->SetColor(gray);
 
       m_LabelSet->AddLabel(label);
     }
   }
 
 public:
   void setUp() override
   {
     m_InitialNumberOfLabels = 6;
     m_LabelSet = mitk::LabelSet::New();
 
     this->AddLabels(m_InitialNumberOfLabels);
     m_LabelSet->SetLayer(0);
     m_LabelSet->SetActiveLabel(0);
   }
 
   void tearDown() override
   {
     m_LabelSet = nullptr;
   }
 
   void TestSetLayer()
   {
     CPPUNIT_ASSERT_MESSAGE("Wrong initial layer", m_LabelSet->GetLayer() == 0);
 
     m_LabelSet->SetLayer(1);
     CPPUNIT_ASSERT_MESSAGE("Wrong layer", m_LabelSet->GetLayer() == 1);
   }
 
   void TestSetActiveLabel()
   {
     CPPUNIT_ASSERT_MESSAGE("Wrong initial active label", m_LabelSet->GetActiveLabel()->GetValue() == 0);
 
     m_LabelSet->SetActiveLabel(1);
     CPPUNIT_ASSERT_MESSAGE("Wrong layer", m_LabelSet->GetActiveLabel()->GetValue() == 1);
   }
 
   void TestRemoveLabel()
   {
     CPPUNIT_ASSERT_MESSAGE("Wrong initial number of label", m_LabelSet->GetNumberOfLabels() == m_InitialNumberOfLabels);
 
     // Remove a label that is not the active label
     m_LabelSet->SetActiveLabel(2);
     m_LabelSet->RemoveLabel(1);
 
     mitk::LabelSet::PixelType numLabels = m_InitialNumberOfLabels - 1;
 
     CPPUNIT_ASSERT_MESSAGE("Label was not removed", m_LabelSet->ExistLabel(1) == false);
     CPPUNIT_ASSERT_MESSAGE("Wrong number of label", m_LabelSet->GetNumberOfLabels() == numLabels);
     CPPUNIT_ASSERT_MESSAGE("Wrong active label", m_LabelSet->GetActiveLabel()->GetValue() == 2);
 
     // Remove active label - now the succeeding label should be active
     m_LabelSet->RemoveLabel(2);
     CPPUNIT_ASSERT_MESSAGE("Wrong layer", m_LabelSet->GetActiveLabel()->GetValue() == 3);
     CPPUNIT_ASSERT_MESSAGE("Label was not removed", m_LabelSet->ExistLabel(2) == false);
     CPPUNIT_ASSERT_MESSAGE("Wrong initial number of label", m_LabelSet->GetNumberOfLabels() == --numLabels);
   }
 
   void TestAddLabel()
   {
     auto newLabel = mitk::Label::New();
     newLabel->SetValue(1);
     m_LabelSet->AddLabel(newLabel);
 
     // Since label with value 1 already exists the new label will get the value m_InitialNumberOfValues
     CPPUNIT_ASSERT_MESSAGE("Wrong label value", m_LabelSet->GetActiveLabel()->GetValue() == m_InitialNumberOfLabels);
-    CPPUNIT_ASSERT_MESSAGE("Wrong number of label", m_LabelSet->GetNumberOfLabels() == m_InitialNumberOfLabels + 1);
+    CPPUNIT_ASSERT_MESSAGE("Wrong number of label", m_LabelSet->GetNumberOfLabels() == static_cast<decltype(m_LabelSet->GetNumberOfLabels())>(m_InitialNumberOfLabels + 1));
   }
 
   void TestRenameLabel()
   {
     const mitk::Color white(1.0f);
     const std::string name = "MyAwesomeLabel";
 
     m_LabelSet->RenameLabel(0, name, white);
 
     const auto* label = m_LabelSet->GetLabel(0);
     CPPUNIT_ASSERT_MESSAGE("Wrong label name", label->GetName() == name );
 
     const auto& color = label->GetColor();
     CPPUNIT_ASSERT_MESSAGE("Wrong color", color == white);
   }
 
   void TestSetAllLabelsVisible()
   {
     const auto numLabels = static_cast<mitk::LabelSet::PixelType>(m_LabelSet->GetNumberOfLabels());
 
     m_LabelSet->SetAllLabelsVisible(true);
 
     for (mitk::LabelSet::PixelType i = 0; i < numLabels; ++i)
       CPPUNIT_ASSERT_MESSAGE("Label not visible", m_LabelSet->GetLabel(i)->GetVisible() == true);
 
     m_LabelSet->SetAllLabelsVisible(false);
 
     for (mitk::LabelSet::PixelType i = 0; i < numLabels; ++i)
       CPPUNIT_ASSERT_MESSAGE("Label visible", m_LabelSet->GetLabel(i)->GetVisible() == false);
   }
 
   void TestSetAllLabelsLocked()
   {
     const auto numLabels = static_cast<mitk::LabelSet::PixelType>(m_LabelSet->GetNumberOfLabels());
 
     m_LabelSet->SetAllLabelsLocked(true);
 
     for (mitk::LabelSet::PixelType i = 0; i < numLabels; ++i)
       CPPUNIT_ASSERT_MESSAGE("Label not locked", m_LabelSet->GetLabel(i)->GetLocked() == true);
 
     m_LabelSet->SetAllLabelsLocked(false);
 
     for (mitk::LabelSet::PixelType i = 0; i < numLabels; ++i)
       CPPUNIT_ASSERT_MESSAGE("Label locked", m_LabelSet->GetLabel(i)->GetLocked() == false);
   }
 
   void TestRemoveAllLabels()
   {
     m_LabelSet->RemoveAllLabels();
     CPPUNIT_ASSERT_MESSAGE("Not all labels were removed", m_LabelSet->GetNumberOfLabels() == 0);
   }
 };
 
 MITK_TEST_SUITE_REGISTRATION(mitkLabelSet)