X devel libs problem?

[Louis Garcia II]

Compiling gst-ffmpeg-0.10.1 on FC6 I ran into this:

gcc -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
-fstack-protector --param=ssp-buffer-size=4 -m32 -march=i386
-mtune=generic -fasynchronous-unwind-tables -Wall -Wno-switch -o ffplay
ffplay-cmdutils.o ffplay-ffplay.o  -L/usr/lib -lSDL -lpthread
libavutil/.libs/libavutil.a libavformat/.libs/libavformat.a -ldl
libavcodec/.libs/libavcodec.a -lz -lm
ffplay-ffplay.o: In function `main':
/usr/src/redhat/BUILD/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg/ffplay.c:2451: undefined reference to `XOpenDisplay'
/usr/src/redhat/BUILD/gst-ffmpeg-0.10.1/gst-libs/ext/ffmpeg/ffplay.c:2455: undefined reference to `XCloseDisplay'
collect2: ld returned 1 exit status
make[7]: *** [ffplay] Error 1

I do have libX11-devel installed but somehow it's not picking it up.
Might this package be screwed up? Don't know if this is an X bug or this
particular package.

-Louis