diff --git a/CMakeExternals/ZLIB.cmake b/CMakeExternals/ZLIB.cmake
index d4706944b6..458878b8b3 100644
--- a/CMakeExternals/ZLIB.cmake
+++ b/CMakeExternals/ZLIB.cmake
@@ -1,73 +1,73 @@
 #------------------------------------------------------------------
 # ZLIB
 #------------------------------------------------------------------
 if(MITK_USE_ZLIB)
 
   set(proj ZLIB)
   set(proj_DEPENDENCIES )
   set(ZLIB_DEPENDS ${proj})
 
   if(NOT DEFINED ZLIB_DIR)
 
     set(additional_cmake_args )
     if(CTEST_USE_LAUNCHERS)
       list(APPEND additional_cmake_args
         "-DCMAKE_PROJECT_${proj}_INCLUDE:FILEPATH=${CMAKE_ROOT}/Modules/CTestUseLaunchers.cmake"
       )
     endif()
 
     # Using the ZLIB from CTK:
     # https://github.com/commontk/zlib
     ExternalProject_Add(${proj}
       LIST_SEPARATOR ${sep}
       URL ${MITK_THIRDPARTY_DOWNLOAD_PREFIX_URL}/zlib-66a75305.tar.gz
       URL_MD5 "4c3f572b487ae7947fd88ec363533bc5"
       CMAKE_ARGS
         ${ep_common_args}
         ${additional_cmake_args}
       CMAKE_CACHE_ARGS
         ${ep_common_cache_args}
         -DBUILD_SHARED_LIBS:BOOL=OFF
         -DZLIB_MANGLE_PREFIX:STRING=mitk_zlib_
         -DZLIB_INSTALL_INCLUDE_DIR:STRING=include/mitk_zlib
       CMAKE_CACHE_DEFAULT_ARGS
         ${ep_common_cache_default_args}
       DEPENDS ${proj_DEPENDENCIES}
       )
     set(ZLIB_DIR ${ep_prefix})
     set(ZLIB_INCLUDE_DIR ${ZLIB_DIR}/include/mitk_zlib)
 
     install(DIRECTORY ${ZLIB_INCLUDE_DIR}
             DESTINATION include
             COMPONENT dev)
 
     find_library(ZLIB_LIBRARY_RELEASE NAMES zlib
                  PATHS ${ZLIB_DIR}
                  PATH_SUFFIXES lib lib/Release
                  NO_DEFAULT_PATH)
     find_library(ZLIB_LIBRARY_DEBUG NAMES zlibd
                  PATHS ${ZLIB_DIR}
                  PATH_SUFFIXES lib lib/Debug
                  NO_DEFAULT_PATH)
 
     set(ZLIB_LIBRARY )
     if(ZLIB_LIBRARY_RELEASE)
-      list(APPEND ZLIB_LIBRARY optimized ${ZLIB_LIBRARY_RELEASE})
+      list(APPEND ZLIB_LIBRARY ${ZLIB_LIBRARY_RELEASE})
       install(FILES ${ZLIB_LIBRARY_RELEASE}
               DESTINATION lib
               CONFIGURATIONS Release
               COMPONENT dev)
     endif()
     if(ZLIB_LIBRARY_DEBUG)
-      list(APPEND ZLIB_LIBRARY debug ${ZLIB_LIBRARY_DEBUG})
+      list(APPEND ZLIB_LIBRARY ${ZLIB_LIBRARY_DEBUG})
       install(FILES ${ZLIB_LIBRARY_DEBUG}
               DESTINATION lib
               CONFIGURATIONS Debug
               COMPONENT dev)
     endif()
 
   else()
     mitkMacroEmptyExternalProject(${proj} "${proj_DEPENDENCIES}")
   endif()
 endif()