diff --git a/CMakeExternals/Numpy.cmake b/CMakeExternals/Numpy.cmake
index 171fc41833..3e47b245d5 100644
--- a/CMakeExternals/Numpy.cmake
+++ b/CMakeExternals/Numpy.cmake
@@ -1,98 +1,97 @@
 #-----------------------------------------------------------------------------
 # Numpy
 #-----------------------------------------------------------------------------
 if( MITK_USE_Python AND NOT MITK_USE_SYSTEM_PYTHON )
   # Sanity checks
   if(DEFINED Numpy_DIR AND NOT EXISTS ${Numpy_DIR})
     message(FATAL_ERROR "Numpy_DIR variable is defined but corresponds to non-existing directory")
   endif()
 
   if( NOT DEFINED Numpy_DIR )
     set(proj Numpy)
     set(${proj}_DEPENDENCIES Python)
     set(Numpy_DEPENDS ${proj})
 
     # setup build environment and disable fortran, blas and lapack
     set(_numpy_env
         "
         set(ENV{F77} \"\")
         set(ENV{F90} \"\")
         set(ENV{FFLAGS} \"\")
         set(ENV{ATLAS} \"None\")
         set(ENV{BLAS} \"None\")
         set(ENV{LAPACK} \"None\")
         set(ENV{MKL} \"None\")
         set(ENV{VS_UNICODE_OUTPUT} \"\")
         set(ENV{CC} \"${CMAKE_C_COMPILER} ${CMAKE_C_COMPILER_ARG1}\")
         set(ENV{CFLAGS} \"${CMAKE_C_FLAGS} ${CMAKE_C_FLAGS_RELEASE}\")
         set(ENV{CXX} \"${CMAKE_CXX_COMPILER} ${CMAKE_CXX_COMPILER_ARG1}\")
         set(ENV{CXXFLAGS} \"${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_RELEASE}\")
         set(ENV{LDFLAGS} \"${CMAKE_LINKER_FLAGS} ${CMAKE_LINKER_FLAGS_RELEASE}\")
 
         ")
 
     set(_numpy_build_step ${MITK_SOURCE_DIR}/CMake/mitkFunctionExternalPythonBuildStep.cmake)
 
     set(_configure_step ${CMAKE_BINARY_DIR}/${proj}-cmake/${proj}_configure_step.cmake)
     file(WRITE ${_configure_step}
        "${_numpy_env}
         include(\"${_numpy_build_step}\")
         file(WRITE \"${CMAKE_BINARY_DIR}/${proj}-src/site.cfg\" \"\")
         mitkFunctionExternalPythonBuildStep(${proj} configure \"${PYTHON_EXECUTABLE}\" \"${CMAKE_BINARY_DIR}\" setup.py config)
        ")
 
     # build step
     set(_build_step ${CMAKE_BINARY_DIR}/${proj}-cmake/${proj}_build_step.cmake)
     file(WRITE ${_build_step}
        "${_numpy_env}
         include(\"${_numpy_build_step}\")
         mitkFunctionExternalPythonBuildStep(${proj} build \"${PYTHON_EXECUTABLE}\" \"${CMAKE_BINARY_DIR}\" setup.py build --fcompiler=none)
        ")
 
     # install step
     set(_install_dir "${Python_DIR}")
     if(WIN32)
       STRING(REPLACE "/" "\\\\" _install_dir ${Python_DIR})
-    else()
-      # escape scpaces on unix
-      STRING(REPLACE " " "\ " _install_dir ${Python_DIR})
     endif()
+    # escape spaces in install path
+    STRING(REPLACE " " "\\ " _install_dir ${_install_dir})
 
     set(_install_step ${CMAKE_BINARY_DIR}/${proj}-cmake/${proj}_install_step.cmake)
     file(WRITE ${_install_step}
        "${_numpy_env}
         include(\"${_numpy_build_step}\")
-        mitkFunctionExternalPythonBuildStep(${proj} install \"${PYTHON_EXECUTABLE}\" \"${CMAKE_BINARY_DIR}\" setup.py install --prefix=\"${_install_dir}\")
+        mitkFunctionExternalPythonBuildStep(${proj} install \"${PYTHON_EXECUTABLE}\" \"${CMAKE_BINARY_DIR}\" setup.py install --prefix=${_install_dir})
        ")
 
     set(Numpy_URL ${MITK_THIRDPARTY_DOWNLOAD_PREFIX_URL}/numpy-1.4.1.tar.gz)
     set(Numpy_MD5 "5c7b5349dc3161763f7f366ceb96516b")
 
     # escape spaces
     if(UNIX)
       STRING(REPLACE " " "\ " _configure_step ${_configure_step})
       STRING(REPLACE " " "\ " _build_step ${_build_step})
       STRING(REPLACE " " "\ " _install_step ${_install_step})
     endif()
 
     ExternalProject_Add(${proj}
       URL ${Numpy_URL}
       URL_MD5 ${Numpy_MD5}
       SOURCE_DIR ${proj}-src
       PREFIX ${proj}-cmake
       BUILD_IN_SOURCE 1
       CONFIGURE_COMMAND ${CMAKE_COMMAND} -P ${_configure_step}
       BUILD_COMMAND   ${CMAKE_COMMAND} -P ${_build_step}
       INSTALL_COMMAND ${CMAKE_COMMAND} -P ${_install_step}
 
       DEPENDS
         ${${proj}_DEPENDENCIES}
     )
 
     set(Numpy_DIR ${MITK_PYTHON_SITE_DIR}/numpy)
 
   else()
     mitkMacroEmptyExternalProject(${proj} "${proj_DEPENDENCIES}")
   endif()
 endif()