diff --git a/code/io/itk/rttbITKImageMaskAccessorGenerator.h b/code/io/itk/rttbITKImageMaskAccessorGenerator.h
index 9736e85..fcb73ed 100644
--- a/code/io/itk/rttbITKImageMaskAccessorGenerator.h
+++ b/code/io/itk/rttbITKImageMaskAccessorGenerator.h
@@ -1,67 +1,69 @@
 // -----------------------------------------------------------------------
 // RTToolbox - DKFZ radiotherapy quantitative evaluation library
 //
 // Copyright (c) German Cancer Research Center (DKFZ),
 // Software development for Integrated Diagnostics and Therapy (SIDT).
 // ALL RIGHTS RESERVED.
 // See rttbCopyright.txt or
 // http://www.dkfz.de/en/sidt/projects/rttb/copyright.html
 //
 // This software is distributed WITHOUT ANY WARRANTY; without even
 // the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 // PURPOSE.  See the above copyright notices for more information.
 //
 //------------------------------------------------------------------------
 /*!
 // @file
 // @version $Revision$ (last changed revision)
 // @date    $Date$ (last change date)
 // @author  $Author$ (last changed by)
 */
 #ifndef __ITK_IMAGE_MASK_ACCESSOR_GENERATOR_H
 #define __ITK_IMAGE_MASK_ACCESSOR_GENERATOR_H
 
 #include "rttbBaseType.h"
 #include "rttbITKImageMaskAccessor.h"
 #include "rttbMaskAccessorGeneratorBase.h"
 
 #include "itkImage.h"
 
+#include "RTTBITKIOExports.h"
+
 namespace rttb
 {
 	namespace io
 	{
 		namespace itk
 		{
 
-			class ITKImageMaskAccessorGenerator: public core::MaskAccessorGeneratorBase
+            class RTTBITKIO_EXPORT ITKImageMaskAccessorGenerator : public core::MaskAccessorGeneratorBase
 			{
 			public:
 				typedef MaskAccessorGeneratorBase::MaskAccessorPointer MaskAccessorPointer;
 
 			private:
 				/** @brief The Mask as itkImage */
 				ITKImageMaskAccessor::ITKMaskImageType::ConstPointer _maskPtr;
 
 				ITKImageMaskAccessorGenerator();
 
 			public:
 				virtual ~ITKImageMaskAccessorGenerator() {};
 
 				/*!
 				@pre aMaskImage must point to a valid instance.
 				@exception InvalidDoseException Thrown if aMaskImage is invalid.
 				*/
 				ITKImageMaskAccessorGenerator(const ITKImageMaskAccessor::ITKMaskImageType* aMaskImage);
 
 				/*! @brief Generate MaskAccessor
 				@return Return shared pointer of MaskAccessor.
 				*/
 				MaskAccessorPointer generateMaskAccessor() ;
 
 			};
 		}
 	}
 }
 
 #endif