MACRO(USE_OPENPASS)
  FIND_PACKAGE(OPENPASS)
  IF ((NOT OPENPASS_FOUND) AND (${ARGC} LESS 1))
    USING_MESSAGE("Skipping because of missing OPENPASS")
    RETURN()
  ENDIF((NOT OPENPASS_FOUND) AND (${ARGC} LESS 1))
  IF(NOT OPENPASS_USED AND OPENPASS_FOUND)
    SET(OPENPASS_USED TRUE)
    INCLUDE_DIRECTORIES(SYSTEM ${OPENPASS_INCLUDE_DIRS})
    SET(EXTRA_LIBS ${EXTRA_LIBS} ${OPENPASS_LIBRARIES})
  ENDIF()
ENDMACRO(USE_OPENPASS)