if(NOT MSGPACK_INCLUDE_PATH)
  set(MSGPACK_URL "https://github.com/msgpack/msgpack-c/releases/download/cpp-2.1.1/msgpack-2.1.1.tar.gz")
  set(MSGPACK_PATH "${CMAKE_CURRENT_BINARY_DIR}/msgpack-2.1.1.tar.gz")
  set(MSGPACK_EXTRACT_PATH "${CMAKE_CURRENT_BINARY_DIR}/msgpack-2.1.1")
  set(MSGPACK_SHA256 "fce702408f0d228a1b9dcab69590d6a94d3938f694b95c9e5e6249617e98d83f")

  file(DOWNLOAD ${MSGPACK_URL} ${MSGPACK_PATH} EXPECTED_HASH SHA256=${MSGPACK_SHA256})

  add_custom_command(
      OUTPUT ${MSGPACK_EXTRACT_PATH}
      COMMAND ${CMAKE_COMMAND} -E tar xzf ${MSGPACK_PATH}
  )
  set(MSGPACK_INCLUDE_PATH "${MSGPACK_EXTRACT_PATH}/include")
  add_custom_target(msgpack-c DEPENDS ${MSGPACK_EXTRACT_PATH} ${SIX_LOC})
else()
  add_custom_target(msgpack-c ${SIX_LOC})
endif()

include_directories(${MSGPACK_INCLUDE_PATH})