If I try to compile musicpd with the adplug option enabled then I get the following error message.

libdecoder_plugins.a(libdecoder_plugins_a-AdPlugDecoderPlugin.o): In function `adplug_scan_file(c[8/3705]
t*, tag_handler const*, void*)':
AdPlugDecoderPlugin.cxx:(.text._ZL16adplug_scan_filePKcPK11tag_handlerPv+0x67): undefined reference to `C
AdPlug::factory(std::string const&, Copl*, CPlayers const&, CFileProvider const&)'
libdecoder_plugins.a(libdecoder_plugins_a-AdPlugDecoderPlugin.o): In function `adplug_file_decode(Decoder
&, char const*)':
AdPlugDecoderPlugin.cxx:(.text._ZL18adplug_file_decodeR7DecoderPKc+0x65): undefined reference to `CAdPlug
::factory(std::string const&, Copl*, CPlayers const&, CFileProvider const&)'
collect2: error: ld returned 1 exit status
Makefile:4356: recipe for target 'src/mpd' failed
gmake[3]: *** [src/mpd] Error 1
gmake[3]: Leaving directory '/usr/ports/audio/musicpd/work/mpd-0.18.11'
Makefile:3235: recipe for target 'all' failed
gmake[2]: *** [all] Error 2
gmake[2]: Leaving directory '/usr/ports/audio/musicpd/work/mpd-0.18.11'
===> Compilation failed unexpectedly.
Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
the maintainer.
*** Error code 1

Stop.
make[1]: stopped in /usr/ports/audio/musicpd
*** Error code 1

Stop.
make: stopped in /usr/ports/audio/musicpd

Using 10.1-RELEASE with latest patches.