diff --git a/Core/CMakeLists.txt b/Core/CMakeLists.txt
index 181090590a..ae64924278 100644
--- a/Core/CMakeLists.txt
+++ b/Core/CMakeLists.txt
@@ -1,48 +1,50 @@
 #-----------------------------------------------------------------------------
 # Configure the CppMicroServices build
 #-----------------------------------------------------------------------------
 
 set(US_ENABLE_AUTOLOADING_SUPPORT ON)
 set(US_ENABLE_THREADING_SUPPORT ON)
 
 # Don't create a "doc" target and don't install the documentation files
 set(US_NO_DOCUMENTATION ON)
 
 # Don't use an install component for SDK artifacts
 set(US_SDK_INSTALL_COMPONENT "")
 
 if(BUILD_TESTING)
   set(US_BUILD_TESTING ON)
 endif()
 
 set(CppMicroServices_DIR_default "${CMAKE_CURRENT_BINARY_DIR}/CppMicroServices")
-set(CppMicroServices_DIR ${CppMicroServices_DIR_default} CACHE PATH "Path to the CppMicroServices library")
+if(NOT CppMicroServices_DIR)
+  set(CppMicroServices_DIR ${CppMicroServices_DIR_default} CACHE PATH "Path to the CppMicroServices library" FORCE)
+endif()
 mark_as_advanced(CppMicroServices_DIR)
 
 if ("${CppMicroServices_DIR}" STREQUAL "${CppMicroServices_DIR_default}")
   add_subdirectory(CppMicroServices)
 endif()
 
 # create a custom module conf file for CppMicroServices
 function(_generate_cppmicroservices_conf)
   set(MITK_MODULE_NAME_PREFIX "")
   set(MODULE_IS_ENABLED 1)
   set(MODULE_NAME CppMicroServices)
   set(MODULE_TARGET ${MODULE_NAME})
   set(MODULE_EXTRA_CMAKE_CODE "find_package(CppMicroServices NO_MODULE REQUIRED)")
   set(MODULE_INCLUDE_DIRS "\${CppMicroServices_INCLUDE_DIRS}")
   set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "\${US_RUNTIME_LIBRARY_DIRS}")
 
   set(CppMicroServices_CONFIG_FILE "${CMAKE_BINARY_DIR}/${MODULES_CONF_DIRNAME}/CppMicroServicesConfig.cmake" CACHE INTERNAL "Path to module config" FORCE)
   configure_file(${MITK_SOURCE_DIR}/CMake/moduleConf.cmake.in ${CppMicroServices_CONFIG_FILE} @ONLY)
 endfunction()
 
 _generate_cppmicroservices_conf()
 
 #-----------------------------------------------------------------------------
 # Add the MITK Core library
 #-----------------------------------------------------------------------------
 
 set(MITK_DEFAULT_SUBPROJECTS MITK-Core)
 
 add_subdirectory(Code)