if(NOT PREPROCMATH_IS_EXTERNAL_PROJECT)
  set(PREPROCMATH_PREFIX "" CACHE PATH "The path to the prefix of an libpreprocmath installation")
  set(PREPROCMATH_INCLUDE_DIR "" CACHE PATH "The path to the headers of an libpreprocmath installation")
  set(PREPROCMATH_LIBRARY_DIR "" CACHE PATH "The path to the library of an libpreprocmath installation")

  set(_search_paths "")
  if(PREPROCMATH_INCLUDE_DIR AND EXISTS ${PREPROCMATH_INCLUDE_DIR})
    list(APPEND _search_paths ${PREPROCMATH_INCLUDE_DIR})
  endif()
  if(PREPROCMATH_PREFIX AND EXISTS ${PREPROCMATH_PREFIX})
    list(APPEND _search_paths "${PREPROCMATH_PREFIX}/include")
  endif()
  find_path(
    PREPROCMATH_INCLUDE_DIRS
    NAMES preprocmath/params.hpp
    PATHS ${_search_paths})

  set(_search_paths "")
  if(PREPROCMATH_LIBRARY_DIR AND EXISTS ${PREPROCMATH_LIBRARY_DIR})
    list(APPEND _search_paths ${PREPROCMATH_LIBRARY_DIR})
  endif()
  if(PREPROCMATH_PREFIX AND EXISTS ${PREPROCMATH_PREFIX})
    list(APPEND _search_paths "${PREPROCMATH_PREFIX}/lib")
  endif()
  find_library(
    PREPROCMATH_LIBRARIES
    NAMES preprocmath
    PATHS ${_search_paths})
  unset(_search_paths)

  if(PREPROCMATH_INCLUDE_DIRS AND PREPROCMATH_LIBRARIES)
    set(PREPROCMATH_FOUND TRUE)
  endif()

  if(PREPROCMATH_FOUND)
    if(NOT PREPROCMATH_FIND_QUIETLY)
      message(STATUS "Found libpreprocmath")
    endif()
    set(HAVE_PREPROCMATH 1)
  elseif(PREPROCMATH_FOUND)
    if(PREPROCMATH_FIND_REQUIRED)
      message(FATAL_ERROR "Could not find libpreprocmath")
    endif()
  endif()
endif()