Matt, I checked with a colleague who has the same problem building gstreamer-plugins-ffmpeg -- see below; and who found the cause & a workaround. An inspection of config.log created with pkgmk -kw revealed "/usr/bin/ld: cannot find -lX11". Thus we retried with 'LIBRARY_PATH=/usr/X11R6/lib pkgmk' which was successful. Therefore I added a line with 'export LIBRARY_PATH=/usr/X11R6/lib pkgmk' to '/etc/pkgmk.conf' in order to be safe. Perhaps you would like to check whether you have anything defined in your environment that enabled you to build this package without taking these extra measures. prt-get: updating /usr/ports/contrib/gstreamer-plugins-ffmpeg =======> Building '/usr/ports/contrib/gstreamer-plugins-ffmpeg/gstreamer-plugins-ffmpeg#0.10.1-1.pkg.tar.gz'. tar -C /usr/ports/contrib/gstreamer-plugins-ffmpeg/work/src --use-compress-program=gzip -xf /usr/ports/contrib/gstreamer-plugins-ffmpeg/gst-ffmpeg-0.10.1.tar.gz + build + cd gst-ffmpeg-0.10.1 + ./configure LIBS=-lX11 --prefix=/usr checking build system type... i686-pc-linux-gnu checking host system type... i686-pc-linux-gnu checking target system type... i686-pc-linux-gnu checking whether to enable maintainer-specific portions of Makefiles... no configure: configuring gst-ffmpeg for release checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for gcc... gcc checking for C compiler default output file name... configure: error: C compiler cannot create executables See `config.log' for more details. =======> ERROR: Building '/usr/ports/contrib/gstreamer-plugins-ffmpeg/gstreamer-plugins-ffmpeg#0.10.1-1.pkg.tar.gz' failed. Thanks, Theo