diff --git a/Modules/Segmentation/Interactions/mitkFillRegionBaseTool.cpp b/Modules/Segmentation/Interactions/mitkFillRegionBaseTool.cpp
index 525816556b..403b705cd7 100644
--- a/Modules/Segmentation/Interactions/mitkFillRegionBaseTool.cpp
+++ b/Modules/Segmentation/Interactions/mitkFillRegionBaseTool.cpp
@@ -1,145 +1,149 @@
 /*============================================================================
 
 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 "mitkFillRegionBaseTool.h"
 #include "mitkToolManager.h"
 
 #include "mitkBaseRenderer.h"
 #include "mitkDataStorage.h"
 
 #include "mitkITKImageImport.h"
 #include "mitkImageAccessByItk.h"
 
 #include "mitkRenderingManager.h"
 
 #include <itkConnectedThresholdImageFilter.h>
 
 mitk::FillRegionBaseTool::FillRegionBaseTool() : SegTool2D("MouseReleaseOnly")
 {
 }
 
 mitk::FillRegionBaseTool::~FillRegionBaseTool()
 {
 }
 
 void mitk::FillRegionBaseTool::ConnectActionsAndFunctions()
 {
   CONNECT_FUNCTION("Release", OnClick);
 }
 
 
 template <typename TPixel, unsigned int VImageDimension>
 void DoITKRegionGrowing(const itk::Image<TPixel, VImageDimension>* oldSegImage,
   mitk::Image::Pointer& filledRegionImage, itk::Index<VImageDimension> seedIndex, mitk::Label::PixelType& seedLabel )
 {
   typedef itk::Image<TPixel, VImageDimension> InputImageType;
   typedef itk::Image<mitk::Label::PixelType, VImageDimension> OutputImageType;
   typedef itk::ConnectedThresholdImageFilter<InputImageType, OutputImageType> RegionGrowingFilterType;
 
   seedLabel = oldSegImage->GetPixel(seedIndex);
 
   typename OutputImageType::Pointer itkResultImage;
   filledRegionImage = nullptr;
 
   try
   {
     typename RegionGrowingFilterType::Pointer regionGrower = RegionGrowingFilterType::New();
     regionGrower->SetInput(oldSegImage);
     regionGrower->SetReplaceValue(1);
     regionGrower->AddSeed(seedIndex);
 
     regionGrower->SetLower(seedLabel);
     regionGrower->SetUpper(seedLabel);
 
     regionGrower->Update();
     
     itkResultImage = regionGrower->GetOutput();
   }
   catch (const itk::ExceptionObject&)
   {
     return; // can't work
   }
   catch (...)
   {
     return;
   }
   mitk::CastToMitkImage(itkResultImage, filledRegionImage);
 }
 
 void mitk::FillRegionBaseTool::OnClick(StateMachineAction*, InteractionEvent* interactionEvent)
 {
   auto positionEvent = dynamic_cast<mitk::InteractionPositionEvent*>(interactionEvent);
   if (nullptr == positionEvent)
     return;
 
   auto labelSetImage = dynamic_cast<const LabelSetImage*>(this->GetWorkingData());
   if (nullptr == labelSetImage)
   {
     return;
   }
 
   if (!IsPositionEventInsideImageRegion(positionEvent, labelSetImage))
   {
     return;
   }
 
   m_LastEventSender = positionEvent->GetSender();
   m_LastEventSlice = m_LastEventSender->GetSlice();
 
   auto workingSlice = this->GetAffectedWorkingSlice(positionEvent);
 
   auto click = positionEvent->GetPositionInWorld();
 
   m_SeedLabelValue = 0;
   auto fillImage = this->GenerateFillImage(workingSlice, click, m_SeedLabelValue);
 
   if (fillImage.IsNull())
   {
     return; //nothing to fill;
   }
 
   auto label = labelSetImage->GetLabel(m_SeedLabelValue, labelSetImage->GetActiveLayer());
 
   if (label->GetLocked() && label->GetValue()!=labelSetImage->GetActiveLabel()->GetValue())
   {
     ErrorMessage.Send("Label of selected region is locked. Tool operation has no effect.");
     return;
   }
 
   this->PrepareFilling(workingSlice, click);
 
   //as fill region tools should always allow to manipulate active label
   //(that is what the user expects/knows when using tools so far:
   //the active label can always be changed even if locked)
   //we realize that by cloning the relevant label set and changing the lock state
   //this fillLabelSet is used for the transfer.
   auto fillLabelSet = labelSetImage->GetActiveLabelSet()->Clone();
-  fillLabelSet->GetLabel(labelSetImage->GetActiveLabel()->GetValue())->SetLocked(false);
+  auto activeLabelClone = fillLabelSet->GetLabel(labelSetImage->GetActiveLabel()->GetValue());
+  if (nullptr != activeLabelClone)
+  {
+    activeLabelClone->SetLocked(false);
+  }
 
   TransferLabelContent(fillImage, workingSlice, fillLabelSet, 0, labelSetImage->GetExteriorLabel()->GetValue(), false, { {1, m_FillLabelValue} }, m_MergeStyle);
 
   this->WriteBackSegmentationResult(positionEvent, workingSlice);
 
   mitk::RenderingManager::GetInstance()->RequestUpdate(positionEvent->GetSender()->GetRenderWindow());
 }
 
 mitk::Image::Pointer mitk::FillRegionBaseTool::GenerateFillImage(const Image* workingSlice, Point3D seedPoint, mitk::Label::PixelType& seedLabelValue) const
 {
   itk::Index<2> seedIndex;
   workingSlice->GetGeometry()->WorldToIndex(seedPoint, seedIndex);
 
   Image::Pointer fillImage;
 
   AccessFixedDimensionByItk_n(workingSlice, DoITKRegionGrowing, 2, (fillImage, seedIndex, seedLabelValue));
 
   return fillImage;
 }