xinerama_test.c build error

$ gcc xinerama_test.c
/tmp/ccn1OaR0.o:xinerama_test.c:(.text+0x19): undefined reference to `XOpenDisplay'
/tmp/ccn1OaR0.o:xinerama_test.c:(.text+0x42): undefined reference to `XineramaQueryScreens'
/tmp/ccn1OaR0.o:xinerama_test.c:(.text+0x139): undefined reference to `XFree'
/tmp/ccn1OaR0.o:xinerama_test.c:(.text+0x145): undefined reference to `XCloseDisplay'
collect2: error: ld returned 1 exit status

mike@executor ~
$ grep 'XOpenDisplay' /usr/include/X11/Xlib.h
extern Display *XOpenDisplay(