if(NOT FSP_IS_EXTERNAL_PROJECT)
  set(FSP_PREFIX "" CACHE PATH "The path to the prefix of an libfsp installation")
  set(FSP_INCLUDE_DIR "" CACHE PATH "The path to the headers of an libfsp installation")
  set(FSP_LIBRARY_DIR "" CACHE PATH "The path to the library of an libfsp installation")

  set(_search_paths "")
  if(FSP_INCLUDE_DIR AND EXISTS ${FSP_INCLUDE_DIR})
    list(APPEND _search_paths ${FSP_INCLUDE_DIR})
  endif()
  if(FSP_PREFIX AND EXISTS ${FSP_PREFIX})
    list(APPEND _search_paths "${FSP_PREFIX}/include")
  endif()
  find_path(
    FSP_INCLUDE_DIRS
    NAMES fsp/mods.hpp
    PATHS ${_search_paths})

  set(_search_paths "")
  if(FSP_LIBRARY_DIR AND EXISTS ${FSP_LIBRARY_DIR})
    list(APPEND _search_paths ${FSP_LIBRARY_DIR})
  endif()
  if(FSP_PREFIX AND EXISTS ${FSP_PREFIX})
    list(APPEND _search_paths "${FSP_PREFIX}/lib")
  endif()
  find_library(
    FSP_LIBRARIES
    NAMES fsp
    PATHS ${_search_paths})
  unset(_search_paths)

  if(FSP_INCLUDE_DIRS AND FSP_LIBRARIES)
    set(FSP_FOUND TRUE)
  endif()

  if(FSP_FOUND)
    if(NOT FSP_FIND_QUIETLY)
      message(STATUS "Found libfsp")
    endif()
    set(HAVE_FSP 1)
  elseif(FSP_FOUND)
    if(FSP_FIND_REQUIRED)
      message(FATAL_ERROR "Could not find libfsp")
    endif()
  endif()
endif()