```diff
*** m4/libtool.m4       2015-10-10 21:32:20.290957100 +0900
--- ../h2o/libtool.m4   2015-10-11 03:21:36.743491800 +0900
***************
*** 5191,5197 ****
        # The linker will automatically build a .lib file if we build a DLL.
        _LT_TAGVAR(old_archive_from_new_cmds, $1)='true'
        # FIXME: Should let the user specify the lib program.
!       _LT_TAGVAR(old_archive_cmds, $1)='lib -OUT:$oldlib$oldobjs$old_deplibs'
        _LT_TAGVAR(enable_shared_with_static_runtimes, $1)=yes
        ;;
        esac
--- 5191,5203 ----
        # The linker will automatically build a .lib file if we build a DLL.
        _LT_TAGVAR(old_archive_from_new_cmds, $1)='true'
        # FIXME: Should let the user specify the lib program.
!        case $build_os in
!       cygwin*)
!           _LT_TAGVAR(old_archive_cmds, $1)='ar rcs $oldlib $oldobjs $old_deplibs'
!         ;;
!         *)
!           _LT_TAGVAR(old_archive_cmds, $1)='lib /OUT:$oldlib$oldobjs$old_deplibs'
!         ;;
        _LT_TAGVAR(enable_shared_with_static_runtimes, $1)=yes
        ;;
        esac
```